Hi all:
I recently replaced my monitor with an ASUS Pro Art. This monitor allows selecting Adobe RGB mode, and supposedly is factory calibrated (I think it came with an inspection certificate certifying Adobe RGB mode accuracy). I calibrate/profile my monitor with a Spyder 3. I find this hardware/software easy to use, and straight forward. My question is: Up to now I have been using Prophoto RGB in Photoshop. Should I now change this to what I used to use, namely Adobe RGB, so they match? I am a novice in Color Mgt, but have been fortunate in achieving prints that match my monitor.
Thanks in advance, this site has helped me enormously.
Dave in NJ
The simple answer is no, but "a little" context is useful ...
ProPhoto RGB, Adobe RGB, and sRGB are device-agnostic color space definitions. They are the color space encodings that your image processing software should use as a working color space or when exporting image files.
- sRGB was defined in the middle 1990s to model the average characteristics of computer displays. It is a specification designed for 8bit per component RGB image files.
- AdobeRGB (1998) was defined in 1998 to model the characteristics of a CMYK web press. It encompasses a larger color space than sRGB but not so large that it cannot be represented in 8bit per component RGB, it is therefore compatible with both 8bit and 16bit image files.
- ProPhoto RGB was defined in the early-middle 2000s as a super-large color space designed to encompass the maximum colorspace that the leading edge image sensors with up to 16bit quantization could record. Because it is so large, it is only valid for 16bit per component RGB files.
What the graphics system on your computer does when operating in a color managed mode is read the image files and their embedded device-agnostic color space tag. It then takes this data and applies a transformation through the device-specific color space definition, the output of which goes to the graphics adapter to drive the display.
The point of this transformation is ensure that a particular color in your ProPhoto RGB tagged image file, call it {Rx, Gx, Bx}, displayed on Display1, which has been correctly calibrated and profiled with a device-specific colorspace, will look identical to the same image displayed on Display2, another physical display with its own device specific calibration and profile.
What the Spyder 3 hardware and software package does is first calibrate the display to the targets you set and then create a device-specific profile for the operating system to use in applying that transformation. There is little point to setting the display to Adobe RGB since that might or might not actually map to its specific characteristics in every detail.
What you want to do is run the Spyder 3 hardware and software, setting the calibration targets you want for the display (I use 110 CDm^2 for luminance, 1.8 gamma, and white point 5600° K). The hardware and software collaborate to set the display to achieve those targets, then the software writes a color profile for the operating system. You (or the Spyder 3 software) set the operating system to use that profile to properly configure the graphics system.
In Photoshop, you then go to the Color Settings and set up the working color space. For most digital cameras, you want to set the Photoshop color system up for 16bit per component and ProPhoto RGB as the working configuration. This allows the greatest leeway in editing without running into boundary problems as you apply adjustments, and will be translated through the operating system's underlying graphics system (including the device-specific display profile) to image correctly on the display.
When you are ready to output the image to a disk file for the web, you'll want to first convert it to sRGB and then reduce the component bit depth to 8bit. Then you can make JPEGs that fit the most generally accepted standard color space for web presentation.
If you are getting the file ready for a web press, you would convert it to AdobeRGB (1998) color space and output it either in 16bit or 8bit depending on the web press you are working with.
If you are going to print the image to your home printer setup, you want to set up the printing configuration with the paper profile for the ink-paper-printer set you're using. The image will be translated to produce colors on the printer that match what appears on the display.
... so much for "a little bit" of context.
To summarize:
- Use the Spyder 3 to calibrate and profile the display.
- Set the operating system to use that profile in the graphics system
- Set up Photoshop's color settings for 16-bit per component and ProPhoto RGB as working colorspace.*
- Convert to sRGB or AdobeRGB when outputting photos for specific needs.
- Use a color managed printing workflow with paper profiles to ensure a high fidelity match in the print to what you see on screen.
* Note that Lightroom does not have a color settings configuration option. It always works in ProPhoto RGB at 16bit per color as a working environment. LR applies color space transformations and color space profiles to exported images when you're done editing or when you print.
Hope That Helps.™ And doesn't confuse ... !
G