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dotnet drawing api : Color problems when converting indexed8 to 24 bit
Hi,
I'm having a problem converting an indexed8 tiff image to a 24bit image. When I convert it with DrawImage or for example DrawImageUnscaledAndClipped it drops the RGB with one. For example (255,255,255) would become (254,254,254). I've tried the victor image processing library demo version and with it I've no problems. Photoshop also converts it to 24bit correctly. Now I'm asking, what Graphics setting do I need to set to get it to convert the image correctly? I've included part of the code below. Also, is it possible to export a reference to a bitmap from a function? How do I dispose of the bitmap in the function? Or shouldn't I do it? Will it be enough if the caller disposes of it? Thanks, Linus Function OpenImage(ByVal filename As String) As Bitmap Dim image As Bitmap Dim image24 As Bitmap Dim g As Graphics Try image = New Bitmap(filename) image24 = New Bitmap(image.Width, image.Height, Imaging.PixelFormat.Format24bppRgb) g = Graphics.FromImage(image24) ' g.CompositingMode = Drawing2D.CompositingMode.SourceCopy ' g.CompositingQuality = Drawing2D.CompositingQuality.AssumeLinear ' g.InterpolationMode = Drawing2D.InterpolationMode.NearestNeighbor ' g.PixelOffsetMode = Drawing2D.PixelOffsetMode.Half ' g.PageUnit = GraphicsUnit.Pixel ' g.SmoothingMode = Drawing2D.SmoothingMode.None g.DrawImage(image, 0, 0, image.Width, image.Height) image24.Save(filename & "2.png") Catch image24 = Nothing End Try If Not (IsNothing(g)) Then g.Dispose() If Not (IsNothing(image)) Then image.Dispose() OpenImage = image24 'If Not (IsNothing(image24)) Then image24.Dispose()
[quoted text, click to view]
On Mar 31, 1:06 pm, Linus <lsilv...@hotmail.com> wrote: Hi, I just debugged it to this line. It seems just reading in the tiff file will mess up the palette. Can there be anything wrong with the tiff files or is there a bug in the Bitmap class? [quoted text, click to view] > image = New Bitmap(filename) Regards,
Hi,
I can't get Drawimage(image, new point(0,0)) to work. All I get is a black image. I must use a new Rectangle instead otherwise it just copies one point). But I think the problem isn't the scaling or using DrawImage, the problem occurs when I LOAD the image. Regards, Linus On Mar 31, 5:37 pm, "Michael Phillips, Jr." [quoted text, click to view] <mphillip...@nospam.jun0.c0m> wrote:
> I suggest that you create a 24bpp image with the same width and height as > the source and set the resolution to match the original source tiff's > resolution. > > Use the DrawImage method with the Point argument(i.e., DrawImage(image, new > Point(0,0)). > > You should get an unscaled bitblt that unpacks the 8bpp source to a 24bpp > image. > > "Linus" <lsilv...@hotmail.com> wrote in message > > news:6a86a59e-d7bb-4657-95a9-82fe612266ce@a22g2000hsc.googlegroups.com... > > > Hi, > > > I'm having a problem converting an indexed8 tiff image to a 24bit > > image. When I convert it with DrawImage or for example > > DrawImageUnscaledAndClipped it drops the RGB with one. For example > > (255,255,255) would become (254,254,254). I've tried the victor image > > processing library demo version and with it I've no problems. > > Photoshop also converts it to 24bit correctly. Now I'm asking, what > > Graphics setting do I need to set to get it to convert the image > > correctly? I've included part of the code below. Also, is it possible > > to export a reference to a bitmap from a function? How do I dispose of > > the bitmap in the function? Or shouldn't I do it? Will it be enough if > > the caller disposes of it? > > > Thanks, > > Linus > > > Function OpenImage(ByVal filename As String) As Bitmap > > > Dim image As Bitmap > > Dim image24 As Bitmap > > Dim g As Graphics > > > Try > > image = New Bitmap(filename) > > image24 = New Bitmap(image.Width, image.Height, > > Imaging.PixelFormat.Format24bppRgb) > > > g = Graphics.FromImage(image24) > > > ' g.CompositingMode = > > Drawing2D.CompositingMode.SourceCopy > > ' g.CompositingQuality = > > Drawing2D.CompositingQuality.AssumeLinear > > ' g.InterpolationMode = > > Drawing2D.InterpolationMode.NearestNeighbor > > ' g.PixelOffsetMode = Drawing2D.PixelOffsetMode.Half > > ' g.PageUnit = GraphicsUnit.Pixel > > ' g.SmoothingMode = Drawing2D.SmoothingMode.None > > g.DrawImage(image, 0, 0, image.Width, image.Height) > > image24.Save(filename & "2.png") > > Catch > > image24 = Nothing > > End Try > > > If Not (IsNothing(g)) Then g.Dispose() > > If Not (IsNothing(image)) Then image.Dispose() > > OpenImage = image24 > > 'If Not (IsNothing(image24)) Then image24.Dispose() > > > End Function
Hi,
MSPaint opens it ok but it also messes up the palette. it subtracts 1 from R,G and B. Does MSPaint use the same TIFF loaders as VB.NET? The 3rd party library and Photoshop Elements 4.0 reads the image fine. Could I send you the picture, if you have the same problem at least I'll know that there isn't anything wrong with my setup? Regards, Linus On Mar 31, 5:50 pm, "Michael Phillips, Jr." [quoted text, click to view] <mphillip...@nospam.jun0.c0m> wrote:
> The tiff specification is complex. > > Perhaps there is something wrong with your image. > > Does it display with MS Paint? > > If you dump the palette after decoding the image, do you get the same > palette when using another 3rd party library or program? > > "Linus" <lsilv...@hotmail.com> wrote in message > > news:3e2ac525-e387-462c-928c-434fe8aa2ee7@u10g2000prn.googlegroups.com... > > > On Mar 31, 1:06 pm, Linus <lsilv...@hotmail.com> wrote: > > > Hi, > > I just debugged it to this line. It seems just reading in the tiff > > file will mess up the palette. Can there be anything wrong with the > > tiff files or is there a bug in the Bitmap class? > > >> image = New Bitmap(filename) > > > Regards, > > Linus
Hi,
Here's the link to it: http://web.abo.fi/~lsilvand/SEM.tif It's an uncompressed 6 Mb TIFF file. Dimensions:3072x2304. 8-bit indexed. Search for white after you've loaded it in, there should be plenty of it if everythings ok. The problem is that I've got thousands of files just like this one and I'ld hope that there's something wrong with the TIFF loader and not with the program producing these TIFF images. Could a problem with the TIFF image also explain why I get a black image while copying it with DrawImage(image,point()). I always have to use DrawImage(image,rectangle()) to get it to produce and ok image. Regards, Linus On Mar 31, 6:28=A0pm, "Bob Powell [MVP]" <b...@spamkillerbobpowell.net> [quoted text, click to view] wrote:
> You seem to have chosen the best mode for a simple copy. > > Can you post the image that you want to make a copy of? > > -- > -- > Bob Powell [MVP] > Visual C#, System.Drawing > > Ramuseco Limited .NET consultinghttp://www.ramuseco.com > > Find great Windows Forms articles in Windows Forms Tips and Trickshttp://w= ww.bobpowell.net/tipstricks.htm > > Answer those GDI+ questions with the GDI+ FAQhttp://www.bobpowell.net/faqm= ain.htm > > All new articles provide code in C# and VB.NET. > Subscribe to the RSS feeds provided and never miss a new article. > > "Linus" <lsilv...@hotmail.com> wrote in message > > news:6a86a59e-d7bb-4657-95a9-82fe612266ce@a22g2000hsc.googlegroups.com... > > > Hi, > > > I'm having a problem converting an indexed8 tiff image to a 24bit > > image. When I convert it with DrawImage or for example > > DrawImageUnscaledAndClipped it drops the RGB with one. For example > > (255,255,255) would become (254,254,254). I've tried the victor image > > processing library demo version and with it I've no problems. > > Photoshop also converts it to 24bit correctly. Now I'm asking, what > > Graphics setting do I need to set to get it to convert the image > > correctly? I've included part of the code below. Also, is it possible > > to export a reference to a bitmap from a function? How do I dispose of > > the bitmap in the function? Or shouldn't I do it? Will it be enough if > > the caller disposes of it? > > > Thanks, > > Linus > > > =A0 =A0Function OpenImage(ByVal filename As String) As Bitmap > > > =A0 =A0 =A0 =A0Dim image As Bitmap > > =A0 =A0 =A0 =A0Dim image24 As Bitmap > > =A0 =A0 =A0 =A0Dim g As Graphics > > > =A0 =A0 =A0 =A0Try > > =A0 =A0 =A0 =A0 =A0 =A0image =3D New Bitmap(filename) > > =A0 =A0 =A0 =A0 =A0 =A0image24 =3D New Bitmap(image.Width, image.Height,= > > Imaging.PixelFormat.Format24bppRgb) > > > =A0 =A0 =A0 =A0 =A0 =A0g =3D Graphics.FromImage(image24) > > > =A0 =A0 =A0 =A0 =A0 =A0' =A0g.CompositingMode =3D > > Drawing2D.CompositingMode.SourceCopy > > =A0 =A0 =A0 =A0 =A0 =A0' =A0g.CompositingQuality =3D > > Drawing2D.CompositingQuality.AssumeLinear > > =A0 =A0 =A0 =A0 =A0 =A0' =A0g.InterpolationMode =3D > > Drawing2D.InterpolationMode.NearestNeighbor > > =A0 =A0 =A0 =A0 =A0 =A0' =A0g.PixelOffsetMode =3D Drawing2D.PixelOffsetM= ode.Half > > =A0 =A0 =A0 =A0 =A0 =A0' =A0g.PageUnit =3D GraphicsUnit.Pixel > > =A0 =A0 =A0 =A0 =A0 =A0' =A0g.SmoothingMode =3D Drawing2D.SmoothingMode.= None > > =A0 =A0 =A0 =A0 =A0 =A0g.DrawImage(image, 0, 0, image.Width, image.Heigh= t) > > =A0 =A0 =A0 =A0 =A0 =A0image24.Save(filename & "2.png") > > =A0 =A0 =A0 =A0Catch > > =A0 =A0 =A0 =A0 =A0 =A0image24 =3D Nothing > > =A0 =A0 =A0 =A0End Try > > > =A0 =A0 =A0 =A0If Not (IsNothing(g)) Then g.Dispose() > > =A0 =A0 =A0 =A0If Not (IsNothing(image)) Then image.Dispose() > > =A0 =A0 =A0 =A0OpenImage =3D image24 > > =A0 =A0 =A0 =A0'If Not (IsNothing(image24)) Then image24.Dispose() > > > =A0 =A0End Function
Just to add one thing. I tested it with Paint.NET v3.2 and it messed
up the palette but Gimp worked ok. On Mar 31, 6:28=A0pm, "Bob Powell [MVP]" <b...@spamkillerbobpowell.net> [quoted text, click to view] wrote:
> You seem to have chosen the best mode for a simple copy. > > Can you post the image that you want to make a copy of? > > -- > -- > Bob Powell [MVP] > Visual C#, System.Drawing > > Ramuseco Limited .NET consultinghttp://www.ramuseco.com > > Find great Windows Forms articles in Windows Forms Tips and Trickshttp://w= ww.bobpowell.net/tipstricks.htm > > Answer those GDI+ questions with the GDI+ FAQhttp://www.bobpowell.net/faqm= ain.htm > > All new articles provide code in C# and VB.NET. > Subscribe to the RSS feeds provided and never miss a new article. > > "Linus" <lsilv...@hotmail.com> wrote in message > > news:6a86a59e-d7bb-4657-95a9-82fe612266ce@a22g2000hsc.googlegroups.com... > > > Hi, > > > I'm having a problem converting an indexed8 tiff image to a 24bit > > image. When I convert it with DrawImage or for example > > DrawImageUnscaledAndClipped it drops the RGB with one. For example > > (255,255,255) would become (254,254,254). I've tried the victor image > > processing library demo version and with it I've no problems. > > Photoshop also converts it to 24bit correctly. Now I'm asking, what > > Graphics setting do I need to set to get it to convert the image > > correctly? I've included part of the code below. Also, is it possible > > to export a reference to a bitmap from a function? How do I dispose of > > the bitmap in the function? Or shouldn't I do it? Will it be enough if > > the caller disposes of it? > > > Thanks, > > Linus > > > =A0 =A0Function OpenImage(ByVal filename As String) As Bitmap > > > =A0 =A0 =A0 =A0Dim image As Bitmap > > =A0 =A0 =A0 =A0Dim image24 As Bitmap > > =A0 =A0 =A0 =A0Dim g As Graphics > > > =A0 =A0 =A0 =A0Try > > =A0 =A0 =A0 =A0 =A0 =A0image =3D New Bitmap(filename) > > =A0 =A0 =A0 =A0 =A0 =A0image24 =3D New Bitmap(image.Width, image.Height,= > > Imaging.PixelFormat.Format24bppRgb) > > > =A0 =A0 =A0 =A0 =A0 =A0g =3D Graphics.FromImage(image24) > > > =A0 =A0 =A0 =A0 =A0 =A0' =A0g.CompositingMode =3D > > Drawing2D.CompositingMode.SourceCopy > > =A0 =A0 =A0 =A0 =A0 =A0' =A0g.CompositingQuality =3D > > Drawing2D.CompositingQuality.AssumeLinear > > =A0 =A0 =A0 =A0 =A0 =A0' =A0g.InterpolationMode =3D > > Drawing2D.InterpolationMode.NearestNeighbor > > =A0 =A0 =A0 =A0 =A0 =A0' =A0g.PixelOffsetMode =3D Drawing2D.PixelOffsetM= ode.Half > > =A0 =A0 =A0 =A0 =A0 =A0' =A0g.PageUnit =3D GraphicsUnit.Pixel > > =A0 =A0 =A0 =A0 =A0 =A0' =A0g.SmoothingMode =3D Drawing2D.SmoothingMode.= None > > =A0 =A0 =A0 =A0 =A0 =A0g.DrawImage(image, 0, 0, image.Width, image.Heigh= t) > > =A0 =A0 =A0 =A0 =A0 =A0image24.Save(filename & "2.png") > > =A0 =A0 =A0 =A0Catch > > =A0 =A0 =A0 =A0 =A0 =A0image24 =3D Nothing > > =A0 =A0 =A0 =A0End Try > > > =A0 =A0 =A0 =A0If Not (IsNothing(g)) Then g.Dispose() > > =A0 =A0 =A0 =A0If Not (IsNothing(image)) Then image.Dispose() > > =A0 =A0 =A0 =A0OpenImage =3D image24 > > =A0 =A0 =A0 =A0'If Not (IsNothing(image24)) Then image24.Dispose() > > > =A0 =A0End Function
I suggest that you create a 24bpp image with the same width and height as
the source and set the resolution to match the original source tiff's resolution. Use the DrawImage method with the Point argument(i.e., DrawImage(image, new Point(0,0)). You should get an unscaled bitblt that unpacks the 8bpp source to a 24bpp image. [quoted text, click to view] "Linus" <lsilvand@hotmail.com> wrote in message news:6a86a59e-d7bb-4657-95a9-82fe612266ce@a22g2000hsc.googlegroups.com... > Hi, > > I'm having a problem converting an indexed8 tiff image to a 24bit > image. When I convert it with DrawImage or for example > DrawImageUnscaledAndClipped it drops the RGB with one. For example > (255,255,255) would become (254,254,254). I've tried the victor image > processing library demo version and with it I've no problems. > Photoshop also converts it to 24bit correctly. Now I'm asking, what > Graphics setting do I need to set to get it to convert the image > correctly? I've included part of the code below. Also, is it possible > to export a reference to a bitmap from a function? How do I dispose of > the bitmap in the function? Or shouldn't I do it? Will it be enough if > the caller disposes of it? > > Thanks, > Linus > > > Function OpenImage(ByVal filename As String) As Bitmap > > Dim image As Bitmap > Dim image24 As Bitmap > Dim g As Graphics > > Try > image = New Bitmap(filename) > image24 = New Bitmap(image.Width, image.Height, > Imaging.PixelFormat.Format24bppRgb) > > g = Graphics.FromImage(image24) > > ' g.CompositingMode = > Drawing2D.CompositingMode.SourceCopy > ' g.CompositingQuality = > Drawing2D.CompositingQuality.AssumeLinear > ' g.InterpolationMode = > Drawing2D.InterpolationMode.NearestNeighbor > ' g.PixelOffsetMode = Drawing2D.PixelOffsetMode.Half > ' g.PageUnit = GraphicsUnit.Pixel > ' g.SmoothingMode = Drawing2D.SmoothingMode.None > g.DrawImage(image, 0, 0, image.Width, image.Height) > image24.Save(filename & "2.png") > Catch > image24 = Nothing > End Try > > If Not (IsNothing(g)) Then g.Dispose() > If Not (IsNothing(image)) Then image.Dispose() > OpenImage = image24 > 'If Not (IsNothing(image24)) Then image24.Dispose() > > > End Function
The tiff specification is complex.
Perhaps there is something wrong with your image. Does it display with MS Paint? If you dump the palette after decoding the image, do you get the same palette when using another 3rd party library or program? [quoted text, click to view] "Linus" <lsilvand@hotmail.com> wrote in message news:3e2ac525-e387-462c-928c-434fe8aa2ee7@u10g2000prn.googlegroups.com... > On Mar 31, 1:06 pm, Linus <lsilv...@hotmail.com> wrote: > > Hi, > I just debugged it to this line. It seems just reading in the tiff > file will mess up the palette. Can there be anything wrong with the > tiff files or is there a bug in the Bitmap class? > >> image = New Bitmap(filename) > > Regards, > Linus
Ok, that explains a lot, hopefully MS would fix this annoying thing in
net2.0. As I understand it, the palette is 16-bit but the image data is only 8-bit? I use VS 2005 at work and I've tried out a couple of things at home with VS Express 2008, but it also seems to use net2.0. I've tried to add the net3.5 imaging api as a reference but can only find the net2.0 version. Am I doing something wrong? On Mar 31, 8:07=A0pm, "Michael Phillips, Jr." [quoted text, click to view] <mphillip...@nospam.jun0.c0m> wrote:
> I downloaded the tiff. =A0The palette is 16bit grayscale. =A0Each of the 7= 68 > colors in the color map is in the range 0 - 65535. > > The gdi decoder must scale and quantize the color map to create a 256 colo= r > palette with each color in the range 0 - 255 when it decodes it to a 8bpp > indexed bitmap. > > If you wish to preserve the color map, use the Net 3.5 media imaging api a= s > it wraps Microsoft's Windows Imaging Compoment. =A0It has better support f= or > tiff images. > > "Linus" <lsilv...@hotmail.com> wrote in message > > news:7e29157b-5d99-4093-97ce-be2070209423@c19g2000prf.googlegroups.com... > > > Hi, > > MSPaint opens it ok but it also messes up the palette. it subtracts 1 > > from R,G and B. Does MSPaint use the same TIFF loaders as VB.NET? The > > 3rd party library and Photoshop Elements 4.0 reads the image fine. > > Could I send you the picture, if you have the same problem at least > > I'll know that there isn't anything wrong with my setup? > > > Regards, > > Linus > > > On Mar 31, 5:50 pm, "Michael Phillips, Jr." > > <mphillip...@nospam.jun0.c0m> wrote: > >> The tiff specification is complex. > > >> Perhaps there is something wrong with your image. > > >> Does it display with MS Paint? > > >> If you dump the palette after decoding the image, do you get the same > >> palette when using another 3rd party library or program? > > >> "Linus" <lsilv...@hotmail.com> wrote in message > > >>news:3e2ac525-e387-462c-928c-434fe8aa2ee7@u10g2000prn.googlegroups.com..= .. > > >> > On Mar 31, 1:06 pm, Linus <lsilv...@hotmail.com> wrote: > > >> > Hi, > >> > I just debugged it to this line. It seems just reading in the tiff > >> > file will mess up the palette. Can there be anything wrong with the > >> > tiff files or is there a bug in the Bitmap class? > > >> >> =A0 =A0 =A0 =A0 =A0 =A0 image =3D New Bitmap(filename) > > >> > Regards, > >> > Linus
I downloaded the tiff. The palette is 16bit grayscale. Each of the 768
colors in the color map is in the range 0 - 65535. The gdi decoder must scale and quantize the color map to create a 256 color palette with each color in the range 0 - 255 when it decodes it to a 8bpp indexed bitmap. If you wish to preserve the color map, use the Net 3.5 media imaging api as it wraps Microsoft's Windows Imaging Compoment. It has better support for tiff images. [quoted text, click to view] "Linus" <lsilvand@hotmail.com> wrote in message news:7e29157b-5d99-4093-97ce-be2070209423@c19g2000prf.googlegroups.com... > Hi, > MSPaint opens it ok but it also messes up the palette. it subtracts 1 > from R,G and B. Does MSPaint use the same TIFF loaders as VB.NET? The > 3rd party library and Photoshop Elements 4.0 reads the image fine. > Could I send you the picture, if you have the same problem at least > I'll know that there isn't anything wrong with my setup? > > Regards, > Linus > > On Mar 31, 5:50 pm, "Michael Phillips, Jr." > <mphillip...@nospam.jun0.c0m> wrote: >> The tiff specification is complex. >> >> Perhaps there is something wrong with your image. >> >> Does it display with MS Paint? >> >> If you dump the palette after decoding the image, do you get the same >> palette when using another 3rd party library or program? >> >> "Linus" <lsilv...@hotmail.com> wrote in message >> >> news:3e2ac525-e387-462c-928c-434fe8aa2ee7@u10g2000prn.googlegroups.com... >> >> > On Mar 31, 1:06 pm, Linus <lsilv...@hotmail.com> wrote: >> >> > Hi, >> > I just debugged it to this line. It seems just reading in the tiff >> > file will mess up the palette. Can there be anything wrong with the >> > tiff files or is there a bug in the Bitmap class? >> >> >> image = New Bitmap(filename) >> >> > Regards, >> > Linus >
16bpp grayscale was never supported. Since it is suppported in Net 3.5, it
is not likely that gdiplus will add this functionality. You must add references for PresentationCore and WindowsBase. [quoted text, click to view] "Linus" <lsilvand@hotmail.com> wrote in message Ok, that explains a lot, hopefully MS would fix this annoying thing innews:a433c5dd-7afa-4689-a680-0426ae9e3198@d21g2000prf.googlegroups.com... net2.0. As I understand it, the palette is 16-bit but the image data is only 8-bit? I use VS 2005 at work and I've tried out a couple of things at home with VS Express 2008, but it also seems to use net2.0. I've tried to add the net3.5 imaging api as a reference but can only find the net2.0 version. Am I doing something wrong? On Mar 31, 8:07 pm, "Michael Phillips, Jr." [quoted text, click to view] <mphillip...@nospam.jun0.c0m> wrote: > I downloaded the tiff. The palette is 16bit grayscale. Each of the 768 > colors in the color map is in the range 0 - 65535. > > The gdi decoder must scale and quantize the color map to create a 256 > color > palette with each color in the range 0 - 255 when it decodes it to a 8bpp > indexed bitmap. > > If you wish to preserve the color map, use the Net 3.5 media imaging api > as > it wraps Microsoft's Windows Imaging Compoment. It has better support for > tiff images. > > "Linus" <lsilv...@hotmail.com> wrote in message > > news:7e29157b-5d99-4093-97ce-be2070209423@c19g2000prf.googlegroups.com... > > > Hi, > > MSPaint opens it ok but it also messes up the palette. it subtracts 1 > > from R,G and B. Does MSPaint use the same TIFF loaders as VB.NET? The > > 3rd party library and Photoshop Elements 4.0 reads the image fine. > > Could I send you the picture, if you have the same problem at least > > I'll know that there isn't anything wrong with my setup? > > > Regards, > > Linus > > > On Mar 31, 5:50 pm, "Michael Phillips, Jr." > > <mphillip...@nospam.jun0.c0m> wrote: > >> The tiff specification is complex. > > >> Perhaps there is something wrong with your image. > > >> Does it display with MS Paint? > > >> If you dump the palette after decoding the image, do you get the same > >> palette when using another 3rd party library or program? > > >> "Linus" <lsilv...@hotmail.com> wrote in message > > >>news:3e2ac525-e387-462c-928c-434fe8aa2ee7@u10g2000prn.googlegroups.com... > > >> > On Mar 31, 1:06 pm, Linus <lsilv...@hotmail.com> wrote: > > >> > Hi, > >> > I just debugged it to this line. It seems just reading in the tiff > >> > file will mess up the palette. Can there be anything wrong with the > >> > tiff files or is there a bug in the Bitmap class? > > >> >> image = New Bitmap(filename) > > >> > Regards, > >> > Linus
You seem to have chosen the best mode for a simple copy.
Can you post the image that you want to make a copy of? -- -- Bob Powell [MVP] Visual C#, System.Drawing Ramuseco Limited .NET consulting http://www.ramuseco.com Find great Windows Forms articles in Windows Forms Tips and Tricks http://www.bobpowell.net/tipstricks.htm Answer those GDI+ questions with the GDI+ FAQ http://www.bobpowell.net/faqmain.htm All new articles provide code in C# and VB.NET. Subscribe to the RSS feeds provided and never miss a new article. [quoted text, click to view] "Linus" <lsilvand@hotmail.com> wrote in message
news:6a86a59e-d7bb-4657-95a9-82fe612266ce@a22g2000hsc.googlegroups.com... > Hi, > > I'm having a problem converting an indexed8 tiff image to a 24bit > image. When I convert it with DrawImage or for example > DrawImageUnscaledAndClipped it drops the RGB with one. For example > (255,255,255) would become (254,254,254). I've tried the victor image > processing library demo version and with it I've no problems. > Photoshop also converts it to 24bit correctly. Now I'm asking, what > Graphics setting do I need to set to get it to convert the image > correctly? I've included part of the code below. Also, is it possible > to export a reference to a bitmap from a function? How do I dispose of > the bitmap in the function? Or shouldn't I do it? Will it be enough if > the caller disposes of it? > > Thanks, > Linus > > > Function OpenImage(ByVal filename As String) As Bitmap > > Dim image As Bitmap > Dim image24 As Bitmap > Dim g As Graphics > > Try > image = New Bitmap(filename) > image24 = New Bitmap(image.Width, image.Height, > Imaging.PixelFormat.Format24bppRgb) > > g = Graphics.FromImage(image24) > > ' g.CompositingMode = > Drawing2D.CompositingMode.SourceCopy > ' g.CompositingQuality = > Drawing2D.CompositingQuality.AssumeLinear > ' g.InterpolationMode = > Drawing2D.InterpolationMode.NearestNeighbor > ' g.PixelOffsetMode = Drawing2D.PixelOffsetMode.Half > ' g.PageUnit = GraphicsUnit.Pixel > ' g.SmoothingMode = Drawing2D.SmoothingMode.None > g.DrawImage(image, 0, 0, image.Width, image.Height) > image24.Save(filename & "2.png") > Catch > image24 = Nothing > End Try > > If Not (IsNothing(g)) Then g.Dispose() > If Not (IsNothing(image)) Then image.Dispose() > OpenImage = image24 > 'If Not (IsNothing(image24)) Then image24.Dispose() > > > End Function
I started thinking about this and the palette might be 16 bits but it
can only point to 256 colors in the image data. The image is about 6Mb uncompressed and 3072x2304x8bits is about 6Mb, so the image data must be 8 bits. The fact that net2.0 will read in the data and but shift the palette with 1 in R,G,B would suggest TIFF decoder problem. I also got around this problem with this small fix below. The interesting thing is that changing the palette won't fix anything if I resave it as an indexed picture(indexed_newpalette.png), but if I first convert it to 24bit it will save it with right palette. Does anyone know why this is? The new gray palette I create can be in reverse or even random, it doesn't matter, the picture will have the correct gray colors when I convert it to 24bit. Can anyone recommend a good book about VB.NET and GDI+? I bought the "Programming Microsoft Visual Basic 2005: The Language" by Fransesco Balena and found it excellent. A similar book about the GDI+ would be a good thing to have. Thanks for all the replies I've recieved! Dim img As Bitmap =3D New Bitmap("d:\test\R017_100x_03.tif") Dim img24 As Bitmap =3D New Bitmap(3072, 2304, Imaging.PixelFormat.Format24bppRgb) Dim g As Graphics =3D Graphics.FromImage(img24) Dim cp As ColorPalette =3D img.Palette For i As Integer =3D 0 To 255 cp.Entries(i) =3D Color.FromArgb(i, i, i) Next img.Palette =3D cp img.Save("d:\indexed_newpalette.png", Imaging.ImageFormat.Png) g.CompositingMode =3D Drawing2D.CompositingMode.SourceCopy g.CompositingQuality =3D Drawing2D.CompositingQuality.AssumeLinear g.InterpolationMode =3D Drawing2D.InterpolationMode.NearestNeighbor g.PixelOffsetMode =3D Drawing2D.PixelOffsetMode.Half g.PageUnit =3D GraphicsUnit.Pixel g.SmoothingMode =3D Drawing2D.SmoothingMode.None g.DrawImageUnscaledAndClipped(img, New Rectangle(0, 0, img.Width, img.Height)) img24.Save("d:\24bit_newpalette.png", System.Drawing.Imaging.ImageFormat.Png) On Mar 31, 10:57=A0pm, "Michael Phillips, Jr." [quoted text, click to view] <mphillip...@nospam.jun0.c0m> wrote:
> 16bpp grayscale was never supported. =A0Since it is suppported in Net 3.5,= it > is not likely that gdiplus will add this functionality. > > You must add references for PresentationCore and WindowsBase. > > "Linus" <lsilv...@hotmail.com> wrote in message > > news:a433c5dd-7afa-4689-a680-0426ae9e3198@d21g2000prf.googlegroups.com... > Ok, that explains a lot, hopefully MS would fix this annoying thing in > net2.0. As I understand it, the palette is 16-bit but the image data > is only 8-bit? I use VS 2005 at work and I've tried out a couple of > things at home with VS Express 2008, but it also seems to use net2.0. > I've tried to add the net3.5 imaging api as a reference but can only > find the net2.0 version. Am I doing something wrong? > > On Mar 31, 8:07 pm, "Michael Phillips, Jr." > > <mphillip...@nospam.jun0.c0m> wrote: > > I downloaded the tiff. The palette is 16bit grayscale. Each of the 768 > > colors in the color map is in the range 0 - 65535. > > > The gdi decoder must scale and quantize the color map to create a 256 > > color > > palette with each color in the range 0 - 255 when it decodes it to a 8bp= p > > indexed bitmap. > > > If you wish to preserve the color map, use the Net 3.5 media imaging api= > > as > > it wraps Microsoft's Windows Imaging Compoment. It has better support fo= r > > tiff images. > > > "Linus" <lsilv...@hotmail.com> wrote in message > > >news:7e29157b-5d99-4093-97ce-be2070209423@c19g2000prf.googlegroups.com...= > > > > Hi, > > > MSPaint opens it ok but it also messes up the palette. it subtracts 1 > > > from R,G and B. Does MSPaint use the same TIFF loaders as VB.NET? The > > > 3rd party library and Photoshop Elements 4.0 reads the image fine. > > > Could I send you the picture, if you have the same problem at least > > > I'll know that there isn't anything wrong with my setup? > > > > Regards, > > > Linus > > > > On Mar 31, 5:50 pm, "Michael Phillips, Jr." > > > <mphillip...@nospam.jun0.c0m> wrote: > > >> The tiff specification is complex. > > > >> Perhaps there is something wrong with your image. > > > >> Does it display with MS Paint? > > > >> If you dump the palette after decoding the image, do you get the same= > > >> palette when using another 3rd party library or program? > > > >> "Linus" <lsilv...@hotmail.com> wrote in message > > > >>news:3e2ac525-e387-462c-928c-434fe8aa2ee7@u10g2000prn.googlegroups.com= .... > > > >> > On Mar 31, 1:06 pm, Linus <lsilv...@hotmail.com> wrote: > > > >> > Hi, > > >> > I just debugged it to this line. It seems just reading in the tiff > > >> > file will mess up the palette. Can there be anything wrong with the= > > >> > tiff files or is there a bug in the Bitmap class? > > > >> >> image =3D New Bitmap(filename) > > > >> > Regards, > > >> > Linus
The palette in your image consists of 768 colors(i.e., rgb) with each color
in the range 0 - 65535. You image is 8bpp indexed. To convert it to a bitmap, the palette must be 256 colors with each color in the range 0 - 255. Using the most significant 8 bits of the 16bpp color will give you colors in the range 0 - 255. Once you create a grayscale palette, the image must be reindexed. Each pixel with a color closest to the original 16bpp grayscale color will be reindexed from the new 256 color grayscale palette. A color of 65024 will be mapped to 254. So will a color such as 65048. A color such as 65526 will map to 255 and so on. You could read the tiff specification to see the recommended way to carry out the color scaling. Converting to 24bpp unpacks the image. If you pull each 16bpp rgb color out of the colormap and scale it by taking the most significant 8 bits and repack it, you still will have color loss when saving as a bitmap. If you really want to see exactly how the decoder handles the conversion, use the Net 3.5 API. You can dump the 768 16bpp colormap and then covert the image to a 8bpp indexed bitmap and then dump the converted palette. [quoted text, click to view] "Linus" <lsilvand@hotmail.com> wrote in message I started thinking about this and the palette might be 16 bits but itnews:efa8bc7e-00e0-424d-8d28-1287c44f8566@e6g2000prf.googlegroups.com... can only point to 256 colors in the image data. The image is about 6Mb uncompressed and 3072x2304x8bits is about 6Mb, so the image data must be 8 bits. The fact that net2.0 will read in the data and but shift the palette with 1 in R,G,B would suggest TIFF decoder problem. I also got around this problem with this small fix below. The interesting thing is that changing the palette won't fix anything if I resave it as an indexed picture(indexed_newpalette.png), but if I first convert it to 24bit it will save it with right palette. Does anyone know why this is? The new gray palette I create can be in reverse or even random, it doesn't matter, the picture will have the correct gray colors when I convert it to 24bit. Can anyone recommend a good book about VB.NET and GDI+? I bought the "Programming Microsoft Visual Basic 2005: The Language" by Fransesco Balena and found it excellent. A similar book about the GDI+ would be a good thing to have. Thanks for all the replies I've recieved! Dim img As Bitmap = New Bitmap("d:\test\R017_100x_03.tif") Dim img24 As Bitmap = New Bitmap(3072, 2304, Imaging.PixelFormat.Format24bppRgb) Dim g As Graphics = Graphics.FromImage(img24) Dim cp As ColorPalette = img.Palette For i As Integer = 0 To 255 cp.Entries(i) = Color.FromArgb(i, i, i) Next img.Palette = cp img.Save("d:\indexed_newpalette.png", Imaging.ImageFormat.Png) g.CompositingMode = Drawing2D.CompositingMode.SourceCopy g.CompositingQuality = Drawing2D.CompositingQuality.AssumeLinear g.InterpolationMode = Drawing2D.InterpolationMode.NearestNeighbor g.PixelOffsetMode = Drawing2D.PixelOffsetMode.Half g.PageUnit = GraphicsUnit.Pixel g.SmoothingMode = Drawing2D.SmoothingMode.None g.DrawImageUnscaledAndClipped(img, New Rectangle(0, 0, img.Width, img.Height)) img24.Save("d:\24bit_newpalette.png", System.Drawing.Imaging.ImageFormat.Png) On Mar 31, 10:57 pm, "Michael Phillips, Jr." [quoted text, click to view] <mphillip...@nospam.jun0.c0m> wrote: > 16bpp grayscale was never supported. Since it is suppported in Net 3.5, it > is not likely that gdiplus will add this functionality. > > You must add references for PresentationCore and WindowsBase. > > "Linus" <lsilv...@hotmail.com> wrote in message > > news:a433c5dd-7afa-4689-a680-0426ae9e3198@d21g2000prf.googlegroups.com... > Ok, that explains a lot, hopefully MS would fix this annoying thing in > net2.0. As I understand it, the palette is 16-bit but the image data > is only 8-bit? I use VS 2005 at work and I've tried out a couple of > things at home with VS Express 2008, but it also seems to use net2.0. > I've tried to add the net3.5 imaging api as a reference but can only > find the net2.0 version. Am I doing something wrong? > > On Mar 31, 8:07 pm, "Michael Phillips, Jr." > > <mphillip...@nospam.jun0.c0m> wrote: > > I downloaded the tiff. The palette is 16bit grayscale. Each of the 768 > > colors in the color map is in the range 0 - 65535. > > > The gdi decoder must scale and quantize the color map to create a 256 > > color > > palette with each color in the range 0 - 255 when it decodes it to a > > 8bpp > > indexed bitmap. > > > If you wish to preserve the color map, use the Net 3.5 media imaging api > > as > > it wraps Microsoft's Windows Imaging Compoment. It has better support > > for > > tiff images. > > > "Linus" <lsilv...@hotmail.com> wrote in message > > >news:7e29157b-5d99-4093-97ce-be2070209423@c19g2000prf.googlegroups.com... > > > > Hi, > > > MSPaint opens it ok but it also messes up the palette. it subtracts 1 > > > from R,G and B. Does MSPaint use the same TIFF loaders as VB.NET? The > > > 3rd party library and Photoshop Elements 4.0 reads the image fine. > > > Could I send you the picture, if you have the same problem at least > > > I'll know that there isn't anything wrong with my setup? > > > > Regards, > > > Linus > > > > On Mar 31, 5:50 pm, "Michael Phillips, Jr." > > > <mphillip...@nospam.jun0.c0m> wrote: > > >> The tiff specification is complex. > > > >> Perhaps there is something wrong with your image. > > > >> Does it display with MS Paint? > > > >> If you dump the palette after decoding the image, do you get the same > > >> palette when using another 3rd party library or program? > > > >> "Linus" <lsilv...@hotmail.com> wrote in message > > > >>news:3e2ac525-e387-462c-928c-434fe8aa2ee7@u10g2000prn.googlegroups.com... > > > >> > On Mar 31, 1:06 pm, Linus <lsilv...@hotmail.com> wrote: > > > >> > Hi, > > >> > I just debugged it to this line. It seems just reading in the tiff > > >> > file will mess up the palette. Can there be anything wrong with the > > >> > tiff files or is there a bug in the Bitmap class? > > > >> >> image = New Bitmap(filename) > > > >> > Regards, > > >> > Linus
This image doesn't exist...
-- -- Bob Powell [MVP] Visual C#, System.Drawing Ramuseco Limited .NET consulting http://www.ramuseco.com Find great Windows Forms articles in Windows Forms Tips and Tricks http://www.bobpowell.net/tipstricks.htm Answer those GDI+ questions with the GDI+ FAQ http://www.bobpowell.net/faqmain.htm All new articles provide code in C# and VB.NET. Subscribe to the RSS feeds provided and never miss a new article. [quoted text, click to view] "Linus" <lsilvand@hotmail.com> wrote in message Hi,news:6b056f19-4ec0-4e03-8f5d-714f2bea75e2@d21g2000prf.googlegroups.com... Here's the link to it: http://web.abo.fi/~lsilvand/SEM.tif It's an uncompressed 6 Mb TIFF file. Dimensions:3072x2304. 8-bit indexed. Search for white after you've loaded it in, there should be plenty of it if everythings ok. The problem is that I've got thousands of files just like this one and I'ld hope that there's something wrong with the TIFF loader and not with the program producing these TIFF images. Could a problem with the TIFF image also explain why I get a black image while copying it with DrawImage(image,point()). I always have to use DrawImage(image,rectangle()) to get it to produce and ok image. Regards, Linus On Mar 31, 6:28 pm, "Bob Powell [MVP]" <b...@spamkillerbobpowell.net> [quoted text, click to view] wrote:
> You seem to have chosen the best mode for a simple copy. > > Can you post the image that you want to make a copy of? > > -- > -- > Bob Powell [MVP] > Visual C#, System.Drawing > > Ramuseco Limited .NET consultinghttp://www.ramuseco.com > > Find great Windows Forms articles in Windows Forms Tips and > Trickshttp://www.bobpowell.net/tipstricks.htm > > Answer those GDI+ questions with the GDI+ > FAQhttp://www.bobpowell.net/faqmain.htm > > All new articles provide code in C# and VB.NET. > Subscribe to the RSS feeds provided and never miss a new article. > > "Linus" <lsilv...@hotmail.com> wrote in message > > news:6a86a59e-d7bb-4657-95a9-82fe612266ce@a22g2000hsc.googlegroups.com... > > > Hi, > > > I'm having a problem converting an indexed8 tiff image to a 24bit > > image. When I convert it with DrawImage or for example > > DrawImageUnscaledAndClipped it drops the RGB with one. For example > > (255,255,255) would become (254,254,254). I've tried the victor image > > processing library demo version and with it I've no problems. > > Photoshop also converts it to 24bit correctly. Now I'm asking, what > > Graphics setting do I need to set to get it to convert the image > > correctly? I've included part of the code below. Also, is it possible > > to export a reference to a bitmap from a function? How do I dispose of > > the bitmap in the function? Or shouldn't I do it? Will it be enough if > > the caller disposes of it? > > > Thanks, > > Linus > > > Function OpenImage(ByVal filename As String) As Bitmap > > > Dim image As Bitmap > > Dim image24 As Bitmap > > Dim g As Graphics > > > Try > > image = New Bitmap(filename) > > image24 = New Bitmap(image.Width, image.Height, > > Imaging.PixelFormat.Format24bppRgb) > > > g = Graphics.FromImage(image24) > > > ' g.CompositingMode = > > Drawing2D.CompositingMode.SourceCopy > > ' g.CompositingQuality = > > Drawing2D.CompositingQuality.AssumeLinear > > ' g.InterpolationMode = > > Drawing2D.InterpolationMode.NearestNeighbor > > ' g.PixelOffsetMode = Drawing2D.PixelOffsetMode.Half > > ' g.PageUnit = GraphicsUnit.Pixel > > ' g.SmoothingMode = Drawing2D.SmoothingMode.None > > g.DrawImage(image, 0, 0, image.Width, image.Height) > > image24.Save(filename & "2.png") > > Catch > > image24 = Nothing > > End Try > > > If Not (IsNothing(g)) Then g.Dispose() > > If Not (IsNothing(image)) Then image.Dispose() > > OpenImage = image24 > > 'If Not (IsNothing(image24)) Then image24.Dispose() > > > End Function
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