Mac experts: need color help

Post by **CelluloidDisco** » Mon Jul 09, 2007 3:53 pm

Mac displays are colour calibrated and most PC displays are not.
It is advisable not to use an internet format for colour proofing. If you are keeping the image at RGB instead of CMYK (for printing), you should use a TIFF with Adobe RGB profile embedded. The adobe one is the best for then converting to CMYK for printing. The colours in the standard sRGB profile are not as saturated as adobe and don't screw up as much for printing. Never use the AppleRGB one if viewing on a PC. As previously mentioned the gamma is way off to PCs so the contrast will not be accurate. BTW I used to work as an artworker. :oops:

Post by **MovieStuff** » Mon Jul 09, 2007 4:04 pm

CelluloidDisco wrote:Mac displays are colour calibrated and most PC displays are not.
It is advisable not to use an internet format for colour proofing. If you are keeping the image at RGB instead of CMYK (for printing), you should use a TIFF with Adobe RGB profile embedded....

Yeah for printing that's what we always do. I was just curious why images on my website would look so different on his Mac than they do on other people's PCs and Macs. Now I know!

Roger

Post by **Chinese Belle** » Mon Jul 09, 2007 4:29 pm

CelluloidDisco wrote:Mac displays are colour calibrated and most PC displays are not.

This is wrong.
Monitors don't calibrate themselves automatically. There are standard profiles that comes with your OS and/or video card drivers or your monitor profile. There is no special process or technology that Mac monitor goes through to get better colors. In fact, for a while Dell LCDs is quite popular on the Mac community (because they used the same panels as the Apple Cinema Display).

Your statement is based on the popularity of the Mac platform being the traditional platform for print and graphics works. Apple had a standard profile for RGB. It was correct because that is what everyone used - or at least use to (again because of the Mac platform's popularity). Everyone just assumed that files from PC where incorrect. They where not - they where just using a different gamma system.
This is not the same as beng 'color calibrated' on the Macs.

Actual color calibration depends on your video card and display settings and environmental conditions (aka wall color and room lighting) and going through a certain process.

His issue, as I said before, all basically comes down to the gamma standard that is different for Windows and Mac OS.

Post by **mattias** » Tue Jul 10, 2007 1:45 am

Chinese Belle wrote:You can adjust both - but there is still an underlying gamma standard for both.

true, but not quite true. both quicktime and color sync are well aware of the mac gamma, and adjust accordingly. before color sync it was a problem that everything looked brighter on macs, but not anymore. the problem now is that not all software knows about this correction, so resaving or converting perfectly fine images and clips on the mac can make them way too dark, even though the data in them was correct, only the display was corrected for the mac gamma. did that make sense? i guess you have to encounter it to see. converting dv video, which is gamma corrected when displayed, to for example sorenson or divx, is one such case, whereas converting to mpeg-4, which is a gamma aware codec, doesn't cause the problem...

/matt

Post by **mattias** » Tue Jul 10, 2007 1:56 am

Chinese Belle wrote:
CelluloidDisco wrote:Mac displays are colour calibrated and most PC displays are not.
This is wrong.
Monitors don't calibrate themselves automatically

no, but i don't think that's what he meant. mac os is "calibrated", even the default profile is not a straight translation. windows just feeds whatever is in the jpeg directly to the image buffer on the graphics card.

/matt

Post by **Chinese Belle** » Tue Jul 10, 2007 2:06 am

Mattias

Understood perfectly.
For video it is slightly different. Because that itself is driven by another gamma profile.
This is because video playback on many computer desktop applications is driven by the video cards 'overlay' function. A secondary gamma/color profile kicks in separate from your desktop profile. When you adjust the video playback say of your DVD app in your computer, it only affects the video but not the entire desktop.

Post by **mattias** » Tue Jul 10, 2007 2:18 am

Chinese Belle wrote:This is because video playback on many computer desktop applications is driven by the video cards 'overlay' function.

which on the mac is driven by open gl, which is colorsync aware. :-) the problem might be that there seems to be only one getpixels function in quicktime, not one for playback and a separate one for transcoding, which should return the raw pixels.

/matt