images in cross-platform stacks

[Phil Davis]

Hi Mark,

Yes - there are certainly some great reasons to use PNGs. My comments 
really only apply in a particular context, even though I state them as 
absolute.  :o)  I'm really good at that.

Phil

Mark Talluto wrote:

>
> 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