images in cross-platform stacks

[Mark Talluto]

On May 16, 2006, at 8:47 PM, Richard Gaskin wrote:

> Phil Davis wrote:
>> 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!
>
> While the cause is identified, I'm unable to identify the logic  
> behind it.
>
> Screen gamma is a function of display, not file format.  
> GraphicConverter doesn't shift the colors when it displays PNGs.
>
> Rev doesn't alter the display of JPEGs or GIFs -- why single out  
> PNGs in this way, and why try to adjust for screen gamma when the  
> screen is already doing anything that needs to be done there?

This is a question that goes way back to the good Dr. Raney.  I  
remember having a discussion with him about it.  The details are  
fuzzy, but they went something like this:  That is the way it is.


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