Color Space - Are you seeing the real picture?
If you visit some of my entries you will find I usually begin by opening my images into "AIM RGB = Trinitron D65 G1.00" color space. If you're curious about what this means I'll try to explain in general terms what this is all about. Bear in mind that this subject is controversial and hotly debated among digital professionals. (Some believe this system, for making digital manipulations more accurate, to be overkill and not required).
First: A brief introduction to the terms color space, gamut and gamma.
As I understand it, color space, in the digital world, is a term used to describe the transference of color information from the real world onto a computer monitor or television screen. Computer monitors are incapable of displaying all the true colors found in nature so various formulas have been developed to adjust the monitor spectrum to get the best representation possible. These adjustments control how the Red, Green, Blue, color guns affect the color properties of the screen. Two of these mathematical formulas are best know to us as "Adobe RGB 1998" and "sRGB IE C61966 2.1". When a photograph is scanned into a computer and opened in i.e. Photoshop the color information contained in the original scan is mathematically altered so it looks like the original print (as much as is possible).
Another aspect of color space is the term wide gamut. For example "Adobe RGB 1998", "sRGB IE C61966 2.1" and "AIM RGB PRO = Widegamut D65 G1.00" are all wide gamut color spaces. This means that they can handle color that falls outside of the capabilities of a computer monitor. A normal color photograph can contain color information that a computer monitor cannot display (similar to the way some high and low pitched sounds are inaudible to the human ear). If you are going to create prints from your work then you should always use a wide gamut color space. If, on the other hand, all your work is only going to be displayed on a monitor (or the WEB) then you can use a "narrow gamut" color space. All my RetouchPro entries are done with "AIM RGB = Trinitron D65 G1.00" which is a narrow gamut color space.
"Color space" dovetails with Gamma space. Gamma space refers to the settings on your monitor that contain the adjustments for contrast, brightness and full black (Black Point). For the uncalibrated Mac system the gamma setting is 1.72, for the native PC the setting is 2.5. These setting are industry standards that govern manufacture of monitors for the Mac or PC. The "sRGB" specification for a Gamma of 2.2 is an attempt to have a digital image display somewhat the same on both the Mac and a PC. This is particularly important when it concerns the “World Wide Web” because most information on the WEB is not platform dependent. A Mac or PC computer might view the same digital images.
If I haven't lost you, I'll try to explain the perceived advantages of using Gamma 1.00
Both "AIM RGB = Trinitron D65 G1.00" and "AIM RGB PRO = Widegamut D65 G1.00" use a gamma space of 1.00 (G1.00). (Remember that normally, the Mac is set to 1.72 and a PC to 2.5).
When a computer system is set to Gamma 1.00 it’s said to be linearly calibrated and properly balanced. Setting your system to gamma 1.00 is considered important because all corrective filters we use every day are created as pure mathematical manipulations done in linear space. In other words they only work correctly, as intended, when used in a linear color space. When we use a Blur or Unsharp filter, for example, in a color space that is NOT set to gamma 1.00 (i.e. Adobe RGB 1998) it's like applying the filter through a distortion lens. When using a non-linear color space (i.e. Adobe RGB 1998), more filtering is required to do the same job and the results are dirtier with a higher degree of distortion to the image.
You should also be aware that all scanners scan in linear color space (i.e. gamma 1.00) then software is used to adjust the color space to match the monitor. Some poor quality scanners have this color adjustment built in and it cannot be changed. You should be able to reset your scanner back to gamma 1.00.
Using Linear color space - the ins and outs:
When I open an image from RetouchPro into Photoshop it is usually from an "Adobe RGB 1998" or "sRGB IE C61966 2.1" color space. With my default color space set to "AIM RGB = Trinitron D65 G1.00" a profile mismatch screen appears asking if I want to convert the image. The first thing I notice when I click OK is that the open image is a lot lighter in color than normal so my first adjustment is Image\Adjustments\Levels where I reset the image to a better "brightness" level. At the same time I usually adjust the colors to normalize the whites of the image - adjusting the colors until an area that I believe should be white, actually becomes white (or a shade of white).
After making the Levels adjustment I go to work on the image. When I have completed all the step required to repair, retouch or enhance the image I reset it back to Adobe color space before sending on to RetouchPro. I do this by using Image\Mode\Convert to Profile set to "Adobe RGB 1998". If this step is missed the image (in "AIM RGB = Trinitron D65 G1.00" color space) will be much too dark when someone else looks at it on the WEB.
In conclusion, I personally believe there is a noticeable advantage to using a linear color space. This is not a complicated process but your computer must be properly calibrated and the conversion steps need to be completed correctly.
As this is just a brief introduction to the topic, further information (212 pages, be prepared to spend some time here) on system Calibration, Editing Techniques, examples and free tools can be found at the AIM (Accurate Image Manipulation) Color Calibration Web Site at http://aim-dtp.net/aim/index.htm . Although the information is of a technical nature, the writing is generally quite good and easily understood. They also have a complete section on Adobe Photoshop Calibration and Issues.
Ron
If you visit some of my entries you will find I usually begin by opening my images into "AIM RGB = Trinitron D65 G1.00" color space. If you're curious about what this means I'll try to explain in general terms what this is all about. Bear in mind that this subject is controversial and hotly debated among digital professionals. (Some believe this system, for making digital manipulations more accurate, to be overkill and not required).
First: A brief introduction to the terms color space, gamut and gamma.
As I understand it, color space, in the digital world, is a term used to describe the transference of color information from the real world onto a computer monitor or television screen. Computer monitors are incapable of displaying all the true colors found in nature so various formulas have been developed to adjust the monitor spectrum to get the best representation possible. These adjustments control how the Red, Green, Blue, color guns affect the color properties of the screen. Two of these mathematical formulas are best know to us as "Adobe RGB 1998" and "sRGB IE C61966 2.1". When a photograph is scanned into a computer and opened in i.e. Photoshop the color information contained in the original scan is mathematically altered so it looks like the original print (as much as is possible).
Another aspect of color space is the term wide gamut. For example "Adobe RGB 1998", "sRGB IE C61966 2.1" and "AIM RGB PRO = Widegamut D65 G1.00" are all wide gamut color spaces. This means that they can handle color that falls outside of the capabilities of a computer monitor. A normal color photograph can contain color information that a computer monitor cannot display (similar to the way some high and low pitched sounds are inaudible to the human ear). If you are going to create prints from your work then you should always use a wide gamut color space. If, on the other hand, all your work is only going to be displayed on a monitor (or the WEB) then you can use a "narrow gamut" color space. All my RetouchPro entries are done with "AIM RGB = Trinitron D65 G1.00" which is a narrow gamut color space.
"Color space" dovetails with Gamma space. Gamma space refers to the settings on your monitor that contain the adjustments for contrast, brightness and full black (Black Point). For the uncalibrated Mac system the gamma setting is 1.72, for the native PC the setting is 2.5. These setting are industry standards that govern manufacture of monitors for the Mac or PC. The "sRGB" specification for a Gamma of 2.2 is an attempt to have a digital image display somewhat the same on both the Mac and a PC. This is particularly important when it concerns the “World Wide Web” because most information on the WEB is not platform dependent. A Mac or PC computer might view the same digital images.
If I haven't lost you, I'll try to explain the perceived advantages of using Gamma 1.00
Both "AIM RGB = Trinitron D65 G1.00" and "AIM RGB PRO = Widegamut D65 G1.00" use a gamma space of 1.00 (G1.00). (Remember that normally, the Mac is set to 1.72 and a PC to 2.5).
When a computer system is set to Gamma 1.00 it’s said to be linearly calibrated and properly balanced. Setting your system to gamma 1.00 is considered important because all corrective filters we use every day are created as pure mathematical manipulations done in linear space. In other words they only work correctly, as intended, when used in a linear color space. When we use a Blur or Unsharp filter, for example, in a color space that is NOT set to gamma 1.00 (i.e. Adobe RGB 1998) it's like applying the filter through a distortion lens. When using a non-linear color space (i.e. Adobe RGB 1998), more filtering is required to do the same job and the results are dirtier with a higher degree of distortion to the image.
You should also be aware that all scanners scan in linear color space (i.e. gamma 1.00) then software is used to adjust the color space to match the monitor. Some poor quality scanners have this color adjustment built in and it cannot be changed. You should be able to reset your scanner back to gamma 1.00.
Using Linear color space - the ins and outs:
When I open an image from RetouchPro into Photoshop it is usually from an "Adobe RGB 1998" or "sRGB IE C61966 2.1" color space. With my default color space set to "AIM RGB = Trinitron D65 G1.00" a profile mismatch screen appears asking if I want to convert the image. The first thing I notice when I click OK is that the open image is a lot lighter in color than normal so my first adjustment is Image\Adjustments\Levels where I reset the image to a better "brightness" level. At the same time I usually adjust the colors to normalize the whites of the image - adjusting the colors until an area that I believe should be white, actually becomes white (or a shade of white).
After making the Levels adjustment I go to work on the image. When I have completed all the step required to repair, retouch or enhance the image I reset it back to Adobe color space before sending on to RetouchPro. I do this by using Image\Mode\Convert to Profile set to "Adobe RGB 1998". If this step is missed the image (in "AIM RGB = Trinitron D65 G1.00" color space) will be much too dark when someone else looks at it on the WEB.
In conclusion, I personally believe there is a noticeable advantage to using a linear color space. This is not a complicated process but your computer must be properly calibrated and the conversion steps need to be completed correctly.
As this is just a brief introduction to the topic, further information (212 pages, be prepared to spend some time here) on system Calibration, Editing Techniques, examples and free tools can be found at the AIM (Accurate Image Manipulation) Color Calibration Web Site at http://aim-dtp.net/aim/index.htm . Although the information is of a technical nature, the writing is generally quite good and easily understood. They also have a complete section on Adobe Photoshop Calibration and Issues.
Ron
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