mark at maseurope.net
Fri Dec 14 07:01:15 CST 2007
Here's a function that should strip the gamma-correction out of a
file. I can't see any before and after difference in the files I've
tried it on, but maybe it could help. Also, be sure to try it on
copies of your prcious files, as it over-writes the file it works on...
on stripGC pFile
--check for the 'magic bytes' to make sure it's a .png
repeat for each item i in "137,80,78,71,13,10,26,10"
put numtochar(i) after magicStr
put url ("binfile:" & pFile) into pngData
if char 1 to 8 of pngData is not magicStr then exit stripGC
-- find the gamma correction chunk
set the casesensitive to true
put offset("gAMA", pngData) - 4 into chunkStart
if chunkStart = 0 then exit stripGC -- stop if it isn't there
put empty into chunkDataLength
get binarydecode("M",char chunkStart to chunkStart + 3 of
delete char chunkStart to (chunkStart + chunkDataLength + 11)
put pngData into url ("binfile:" & pFile)
On 14 Dec 2007, at 08:22, Scott Rossi wrote:
> Recently, Bridger Maxwell wrote:
>> A friend of mine cooked up a fix. He created an automator action
>> will change all the files from png to jpg by making a new jpg image
>> and pasting the png into it. Apparently, when simply saving the png
>> to a jpg (from Preview) it does not solve the problem. This is
>> definitely a Revolution problem, because the images display just fine
>> in every other program, but I don't even know how to submit a bug
>> this when I am not sure what causes it or exactly why the fix works.
>> Can anyone give me a hint on this?
> As Jacque explained, it probably has to do with the reading (or lack
> thereof) of gamma information in the file.
> FWIW, you might want to see this post from September:
> Scott Rossi
> Creative Director
> Tactile Media, Multimedia & Design
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