JPEG - Color problems
Author
Hi!
There was no answer in the "visual arts" forum - so i will try it at "Game programming":
I am using directx7. I load my .bmp-graphics - all works well.
But if i load the same graphics (using NViewLib.dll) as .jpg, it seems that black (my colorkey) is not really black. For example around yellow colors there are a lot of pixels that appears not transparent. I use Adobe photoshop to save the .bmp as .jpg (highest quality).
Any ideas? It would be nice to use .jpg to get a downloadable game.
Thanks
McMc
In the structure DDCOLORKEY
Did you set both high and low value to black? If so, be careful as jpeg compression doesn''t store images in a similar fashion to gif/bmp. Black areas may not be wholly black and may be approximated over a wide range of values. Give a higher range to the high and low values and see if that makes a difference.
SC
typedef struct _DDCOLORKEY{ DWORD dwColorSpaceLowValue; DWORD dwColorSpaceHighValue;} DDCOLORKEY, FAR* LPDDCOLORKEY; Did you set both high and low value to black? If so, be careful as jpeg compression doesn''t store images in a similar fashion to gif/bmp. Black areas may not be wholly black and may be approximated over a wide range of values. Give a higher range to the high and low values and see if that makes a difference.
SC
I am pretty sure the problem is solved if you don''t use a single color for transparency, but a color-range.
If you use BMPs, the right color for each Pixel is stored, but if you use JPGs compression, it will only store "A color close to the one you wanted". So a JPG black isn''t the same black at all places.
Your eye can''t differ a RGB 0-0-0 black from a 0-1-1 black, but for transperency it does differ.
Hope this helps.
If you use BMPs, the right color for each Pixel is stored, but if you use JPGs compression, it will only store "A color close to the one you wanted". So a JPG black isn''t the same black at all places.
Your eye can''t differ a RGB 0-0-0 black from a 0-1-1 black, but for transperency it does differ.
Hope this helps.
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