images in cross-platform stacks

[Mark Talluto]

On May 16, 2006, at 5:23 PM, Phil Davis wrote:

> I just re-discovered something that might be helpful to others, so  
> here goes.
>
>
> Bottom line:
> To simplify your code and your life, use JPG images, not PNGs, in  
> stacks intended for cross-platform use. That way you don't have to  
> mess with the screenGamma property to make everything look the same  
> everywhere.
>
>
> Situation:
> I have a gray PNG file whose only color is 145,145,145 no matter  
> what tool you use, Mac or PC, to get the color info.
>
> Even from within OSX Rev, if the image file is opened in another  
> app underneath Rev, I can use the color ppicker's magnifying glass  
> to get the color - still 145,145,145.
>
> Then I imported the image into a Rev stack. Boom! The color  
> picker's magnifying glass now says the color in the Rev image  
> object is 123,123,123. What happened?
>
> What happened was the screenGamma, since my image is a PNG file.  
> Rev's screenGamma is a color? or brightness? or ??? adjustment  
> factor applied only to PNG files. The screenGamma defaults are 1.7  
> for Mac and 2.2 for Windows. (I don't know what they are for Linux.)
>
> I then used a graphics tool to convert it to JPG, and re-imported  
> it into a Rev stack. The new image object's color is 145,145,145.
>
> Cause identified!


You can always set the screenGamma and stick with the wonderful  
transparency features that exist in the .png format.


Mark Talluto
-- 
CANELA Software
http://www.canelasoftware.com