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Date Posted: 18:04:34 01/25/01 Thu
Author: Michel
Subject: Re: Wrong color mapping with 256 colors
In reply to: martin 's message, "Wrong color mapping with 256 colors" on 10:22:40 01/25/01 Thu

Hi Martin,

This is a limitation of Envision when your video driver is set to 256 colors or less. When a video driver only has 256 colors or less, the programs need to continuously replace the windows system palette with one optimized for the image being displayed. This is something Envision does not do. In 256 color video modes, Envision will draw the images in the current system palette, and this results in a low quality display, because most of the time the system palette has a different range of colors.

Best regards,


>I use the TImageScrollBox from Envision 1.1 to display
>pictures. The picture file is loaded simply with
>.LoadFromFile(picturePath, 0) and is shown directly in
>the ImageScrollBox.
>When Windows uses High Color or True color, then all
>pictures are shown with correct colors. But when I use
>256 colors (to have a higher screen resolution), then
>wrong colors are used.
>Control Panel -> Display -> Settings -> Color Palette
>When showing a true color picture, e.g. JPEG, with
>256 colors, the colors will not be 100% accurate, but
>they should be at least similar to the original color.
>I think this color conversion is called 'color
>mapping', I'm not sure.
>Other Windows programs show at least a fairly similar
>picture, but not TImageScrollBox. I have tested the
>same situation, true color picture with 256 Window
>colors, with the Delphi component TJPEGImage and
>TJPEGImage shows the picture with correct colors.
>Is this a bug in TImageScrollBox? Is there a

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