"SharpCoderMP" <csharp_mp@interia.pl.NFSPM> wrote in message
news:%23kn9vWtxGHA.3844@TK2MSFTNGP06.phx.gbl...
> hi,
>
> how can i save a grayscale (8bit) image? i tried using
> System.Drawing.Imaging.Encoder.ColorDepth but when i try to save jpeg
> wither using 8 or 1bit i always get 24bit one. when i try to save tiff i
> get an exception when i try 8 or 1bit. what's going on??
>
> here's code example:
>
> using (Bitmap b = new Bitmap(200, 50))
> using (Graphics g = Graphics.FromImage(b))
> using (Font f = new Font(FontFamily.GenericSansSerif, 12))
> using (StringFormat sf = new StringFormat())
> {
> g.PageUnit = GraphicsUnit.Pixel;
> sf.LineAlignment = StringAlignment.Center;
> sf.Alignment = StringAlignment.Center;
> Rectangle rect = new Rectangle(0, 0, b.Width, b.Height);
> g.FillRectangle(Brushes.White, rect);
> g.DrawString(someText, f, Brushes.Black, rect, sf);
> ImageCodecInfo[] codecs = ImageCodecInfo.GetImageEncoders();
> ImageCodecInfo ici = null;
> foreach (ImageCodecInfo codec in codecs)
> {
> if (codec.MimeType == "image/jpeg")
> ici = codec;
> }
> EncoderParameters ep = new EncoderParameters(2);
> ep.Param[0] = new EncoderParameter(
> System.Drawing.Imaging.Encoder.Quality, (long)85);
> ep.Param[1] = new EncoderParameter(
> System.Drawing.Imaging.Encoder.ColorDepth, 8L);
> b.Save(fileName, ici, ep);
> }

"Bob Powell [MVP]" <bob@_spamkiller_.bobpowell.net> wrote in message
news:eN5N$MvxGHA.3492@TK2MSFTNGP02.phx.gbl...
> You can only save a GIF image in 8 bit. You can simulate gray scale by
> creating a monochrom palette.

Bob Powell [MVP] wrote:
> You can only save a GIF image in 8 bit. You can simulate gray scale by
> creating a monochrom palette.

Michael C wrote:
> I can save an 8 bit image to tiff on my machine.
>
> To the OP, your problem is that the bitmap is in 24 or 32 bit format. You
> need to make it an 8 bit indexed image before saving.

"SharpCoderMP" <csharp_mp@interia.pl.NFSPM> wrote in message
news:upq76B2xGHA.3568@TK2MSFTNGP03.phx.gbl...
> Michael C wrote:
>> I can save an 8 bit image to tiff on my machine.
>>
>> To the OP, your problem is that the bitmap is in 24 or 32 bit format. You
>> need to make it an 8 bit indexed image before saving.
>
> can you post some code?

"SharpCoderMP" <csharp_mp@interia.pl.NFSPM> wrote in message
news:%23PynrB2xGHA.3568@TK2MSFTNGP03.phx.gbl...
> you mean indexed palette?
> i don't get it. there are options for encoders, like Encoder.ColorDepth
> but they don't work?? what for are they then?

> i need a 8bit grayscale bitmap file. tiff or jpeg would be nice.
> 24bit image with simulated gray colors won't do the job.

> i also don't understand what for is a Bitmap(int,int,PixelFormat)
> constructor??

> if i use something else than RGB i cant draw anything to
> that bitmap. every time i try to create a Graphics object from such
> bitmap i get exceptions.