Posting Images in Critique

[Ronnoco]

I collect books for useful info. I currently have more than 1,000 in my personal library.
Some interesting info. comparing Mac and PC operating systems relating to posting images on the net. The first interesting question would be how many use PCs here and how many use Macs.

Mac systems apply gamma when they render images to the screen, which considerably boosts brightness. Windows applies no such gamma and equivalent images tend to be darker on the screen.

If you are a Mac user and most here are PC, then your perfectly exposed image according to your Mac monitor will look underexposed on our PC monitors. The answer for Mac users is to boost brightness 10 units before saving the PC version of the image.
The image will look too bright on a Mac monitor but perfect on a PC monitor.

A PC user in a Mac environment would do the reverse and decrease brightness 10 units before saving the Mac version of the image.

Hope this helps to sort out some "exposure" and "brightness" issues that may be occuring in Critique.

Ronnoco

[Sebastian]

Wrong. Both systems apply gamma, Macs used to use the 1.8 setting, PCs use 2.2. Now for the past few years everyone has pretty much standarized for 2.2. When calibrating (software or hardware) the current recommended setting is 2.2 for any system.

[GB1]

Seb - I dont know who's right or wrong here, but the screens do look a little brighter on the Macs I've seen in computer stores when compared to the average PC. But since the brightnesses can be adjusted on the individual monitors, it's hard to say if that's inherent with either computer.

Also if I drop off digital files for printing, the lab I use does not adjust the density at all in this situation (with dig files), and they sometimes come out a little darker than I wanted. I need to figure out how to calibrate my monitor I suppose (ASAP).

gb

[Sebastian]

Yes, Macs use a 1.8 gamma, PCs use 2.2, that's why PCs look darker. To say that one applies gamma and one doesn't is incorrect.

In general, the industry is moving towards the 2.2 setting, and most hardware and software calibration tools recommend 2.2.

[Lava Lamp]

(Please don't edit and repost my images, thank you)

But, Sebastian, I think someone already has. I don't know if you've noticed, but someone marked up your avatar photo with devil horns.

[drg]

Sebastian is correct. Both systems have a gamma setting. Gamma is a color temperature notation. Yes, Windows systems are hotter/brighter; their color temp is significantly higher.

The original viewing standard for proofing stations was D50. That correlates almost exactly to the 1.8 of Macs. The 5000k color now gets competition from and the industry is moving to the D65 or 6500k color temp standard. The overall ease of calibration has led to not only these by other 'standards' as well.

More than brightness or exposure, an incorrect setting in this environment will make a photo look muddy or muted one way and possibly garish in color representation the other way. Brightness and exposure issues are often associated with the monitor's brightness being set wrong! Exposure and brightness issues in critique are often a good issue to bring up as there may be a need for some photographers to learn what a well-exposed photo looks like. Then, you can learn to play with it and go high/low key use over/under exp. to your benefit.

One place that many photos will suffer is the amount of JPEG compression that is applied to them. However, that has been discussed rather extensively in other posts.

An arbitrary number increase/decrease unless everybody is exactly using the same systems, the monitors, crt or lcd, are not getting old and losing their 'punch', is not a particularly great solution no matter how well intended the idea. It is good to note that there can be differences, but let's get them right.

PROFILE PROFILE PROFILE ! (Your monitor, scanner, and camera)

[Ronnoco]

"Your MAC does gamma correction in its graphics card, most PCs do not. Therefore when something looks good on a MAC it will look too dark on a PC." from cgsd.com.

It then goes on to suggest setting gamma within Photoshop and here there is some controversy. Set it in the middle between 1.8 and 2.5 or set it at closer toward 2.5 for others.

Ronnoco

[Sebastian]

"Your MAC does gamma correction in its graphics card, most PCs do not. Therefore when something looks good on a MAC it will look too dark on a PC." from cgsd.com.

I think the point you might be trying to make is that by default, OS X applies a gamma correction as well as color space correction to EVERYTHING displayed on a system-wide level. Whereas Windows depends on third-party apps to apply the same level of consistency, but it's default sRGB profile comes very close to the 2.2 mark. And by third-party I mean that even a driver set for a half-way decent video card will apply said corrections. Hence the appearance of the screen changing when non-generic video card drivers are installed.

An image can be altered in two places on the way to the monitor. (1) by the video lookup table (LUT). This is performed by all the calibration techniques below. (2) by gamut mapping in color-managed workflows, performed by the color engine (CMM) under the control of an ICC monitor profile. See Color management parts 1: Introduction and 2: Implementation for more detail.
The LUT is normally loaded with values that enable the display to operate at the gamma (usually 2.2) specified by the calibration process.

Confusion arises because both transformations take place in color-managed workflows, and both are controlled by an ICC monitor profile. An ICC profile provides data for the LUT loader program, which is run at startup; it also provides information for the gamut mapping between the working color space and the monitor color space. To confuse things further, Photoshop uses the Windows default monitor profile while Picture Window Pro uses a user-selected monitor profile.

This page focuses on calibration.

http://www.normankoren.com/makingfineprints1A.html

If you want the ultimate in monitor-print matching or you can't get good calibration with the visual approach, get a calibrator and upgrade to a color-managed workflow. Luminous-Landscape.com and many other authors strongly recommend this approach. But the improvement over the visual approach may be modest because the Windows-default sRGB color space is close to typical CRT monitors calibrated for gamma = 2.2.

http://www.normankoren.com/makingfineprints1A.html

Your monitor's gamma should be 2.2 or 1.8.

2.2 is recommended for Windows, the Internet sRGB color space, and the popular Adobe RGB (1998) color space. 1.8 is the standard for older Macintosh systems and prepress file interchange (Mac users, see note below). I aim for gamma = 2.2. Most laptop LCD screens are poorly suited for critical image editing because gamma is extremely sensitive to viewing angle.

http://www.normankoren.com/makingfineprints1A.html

Most modern monitors – Mac or PC – have a native gamma near 2.2. A few specialized displays use other values. The traditional Mac gamma of 1.8 is a holdover from the first monochrome Mac displays. Unless that is what your system uses, your graphics editing environment will benefit from changing to a gamma near 2.2. The only drawback is that the Mac GUI elements – menus, buttons, etc. – are designed for a 1.8 gamma display. These elements will appear darker with a system gamma of 2.2, but images displayed in a color managed system will have fewer display artifacts.

http://www.drycreekphoto.com/Learn/C...r_gradient.htm

[Sebastian]

But, Sebastian, I think someone already has. I don't know if you've noticed, but someone marked up your avatar photo with devil horns.

Yeah, you can "blame" Trevor for that one...