Yeah, I have seen this as well.

You can find an interesting conversation about this here:
http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&oe=UTF-8&threadm=%23X%240uJMBDHA.1552%40TK2MSFTNGP12.phx.gbl&rnum=1&prev=/groups%3Fhl%3Den%26lr%3D%26ie%3DUTF-8%26oe%3DUTF-8%26q%3Dwhite%2Bnot%2Bwhite%26meta%3Dgroup%253Dmicrosoft.public.dotnet.framework.compactframework

Basically it is now a known issue.

Thanks,
Chris Craft
http://www.cjcraft.com/

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Hi,

When I display a picture and load a bitmap with whites in it (in fact, a big
white area), and I compare thet white with the full white of the panel
behind it, I see that the bitmap is not exactly white. Is there some color
conversion in the PDA device ? How can I force a full white pixel in a
bitmap to display as the same white as the rest of my application?

Thanks!
Jacco

I use vb .net 2003 to write an application in the compact framework.

Make your bitmap a gif with a transparent attribute
or
use something like this to draw with a transparent attribute...
this is from someone's image button code I found posted here but it can help
you draw with transparency.

protected override void OnPaint(PaintEventArgs e )
{
Graphics gxOff; //Offscreen graphics
Rectangle imgRect; //image rectangle
Brush backBrush; //brush for filling a backcolor
if (m_bmpOffscreen == null) //Bitmap for doublebuffering
{
m_bmpOffscreen = new Bitmap(ClientSize.Width, ClientSize.Height);
}
gxOff = Graphics.FromImage(m_bmpOffscreen);
gxOff.Clear(BackColor);
if (!bPushed)
backBrush = new SolidBrush(Parent.BackColor);
else //change the background when it's pressed
backBrush = new SolidBrush(Color.White);
gxOff.FillRectangle(backBrush, ClientRectangle);
if (image != null)
{
//Center the image relativelly to the control
int imageLeft = (Width - image.Width) / 2;
int imageTop = (Height - image.Height) / 2;
imgRect = new Rectangle(imageLeft , imageTop , image.Width,
image.Height);
//Set transparent key
ImageAttributes imageAttr = new ImageAttributes();
imageAttr.SetColorKey(BackgroundImageColor(image),
BackgroundImageColor(image));
//Draw image
gxOff.DrawImage(image, imgRect, 0, 0, image.Width, image.Height,
GraphicsUnit.Pixel, imageAttr);
}
else
{
}
//Draw from the memory bitmap
e.Graphics.DrawImage(m_bmpOffscreen, 0, 0);
base.OnPaint(e);
}
protected override void OnPaintBackground(PaintEventArgs e )
{
//Do nothing
}
private Color BackgroundImageColor(Image image)
{
Bitmap bmp = new Bitmap(image);
return bmp.GetPixel(0, 0);
}

Hi Boris,

This is simply not possible due to the limitations of the hardware.
Remember that you are taking a bitmap that you have viewed on a display
capable of displaying 24, and most likely 32 bit images and putting it on a
device that is only capable of displaying 16 bit graphics. Just be thankful
you are not working on a video game system that has to display it on an NTSC
screen!

When the pixels are converted, they are "rounded down" so if you want to
preview the graphics on the desktop then take each pixel color and round it
off like it will be on the device. Most devices are 555 RGB formatted so if
you take each pixel, break into R,G, and B components, then right shift by 3
you should see something more similar to what it will be on the device.

--
Geoff Schwab
Program Manager
Excell Data Corporation
http://msdn.com/mobility
http://msdn.microsoft.com/mobility/prodtechinfo/devtools/netcf/FAQ/default.aspx

This posting is provided "AS IS" with no warranties, and confers no rights.
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AHA!
Now that's interesting!
Yesterday evening i've build up a cool startup bitmap for a splash
screen... but on the device it looks a bit "ugly / dirty" ... and i have
searched and thought WHY THE HELL... but now it's clear :'(

Does anyone have some code to work-around that? (code example to use the
native API to set the pixeldepth to 24bit)

Boris

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