Luminous Landscape Forum
Raw & Post Processing, Printing => Colour Management => Topic started by: mephisto2061 on March 03, 2012, 11:17:14 am
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I wanted to understand how calibrating the monitor to a "known standard" e.g. 6500 2.2 helps make prints look similar to how they appear on the screen, with soft proofing. I am not able to grasp how this works if the monitor calibration settings and the printer profile don't "talk" to each other. Obviously a custom printer profile allows my software to simulate how the print would look. But this soft proofing software is simply sending some RGB values to the monitor, right? How does what actually appears on the screen (which is a function of the 6500 2.2 calibration) correspond to what the soft proofing software is trying to display on the screen?
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I wanted to understand how calibrating the monitor to a "known standard" e.g. 6500 2.2 helps make prints look similar to how they appear on the screen, with soft proofing.
There lies the misconceptions. There is no standard that produces a match, only a group that might produce the match. Your mileage (settings) may vary. The right settings are those that produce a visual match. See:http://www.luminous-landscape.com/tutorials/why_are_my_prints_too_dark.shtml
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I see. So the point of monitor calibration to a known standard is only to make my monitor look similar to what other people in the world have presumably calibrated their monitors to (and obviously to have consistency)? That's where the recommendation to calibrate to 6500 2.2 (in some of the LuLa tutorials) comes from rather than anything to do with a print workflow?
On a separate note, the problem I sometimes have with my prints are that some yellows on the screen look reddish (and less warm) on my prints. Darkness is not an issue as I think I've got the optimal brightness settings etc for my monitor. This colour shift despite having custom profiles + soft proofing. I print on a SP3885 and have an Apple Cinema Display.
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I see. So the point of monitor calibration to a known standard is only to make my monitor look similar to what other people in the world have presumably calibrated their monitors to (and obviously to have consistency)? That's where the recommendation to calibrate to 6500 2.2 (in some of the LuLa tutorials) comes from rather than anything to do with a print workflow?
In my opinion, yes. I personally think precise monitor calibration is highly overrated. Even after 'painting the walls grey', fine tuning the lighting and spending thousands on monitor calibration, our eyes will render images differently based on factors we don't yet completely understand. At best, the whole process is a guesstimate. In that case, I say why bother with greater precision, when experience (and knowing your own eyes) can do the same job with far greater emotional satisfaction?
But if one has clients on one's back, it is probably a sane idea to follow the crowd.
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I think that monitor calibration is best described as creating a stable standard. Yes, our eyes/brain can do a tremendous amount of adjusting on the fly without us actually realizing it, but if we eliminate as many of the variables as possible, we stand a better chance of producing consistent colors in our images. Sure, two identical prints viewed under different lighting by different people will be perceived to be different, but if we choose to try to be exactly on target (our desired color/contrast etc) then it surely is easier to hit a stationary target (calibrated monitor) than it is to hit a target that is possibly moving (uncalibrated monitor).
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I see. So the point of monitor calibration to a known standard is only to make my monitor look similar to what other people in the world have presumably calibrated their monitors to (and obviously to have consistency)? That's where the recommendation to calibrate to 6500 2.2 (in some of the LuLa tutorials) comes from rather than anything to do with a print workflow?
You are mistaking "calibration" with "profiling"...in point of fact, it really doesn't matter all that much how you calibrate your display...there are optimal white points and gammas, but that's a different question. But what you absolutely MUST have is an accurate profile of the state of your display. Photoshop and Lightroom use the display profile to alter the on-screen representation of your image. If the display is not accurate, the on-screen presentation won't be accurate. If your display profile is inaccurate, then the on-screen presentation of your image will be inaccurate.
When you throw in soft proofing, it gets even more complicated...regardless of the accuracy of your printer profile, if your display profile is inaccurate, then soft proofing won't work. Same deal with the printer profile. The main reason I think most people think soft proofing doesn't work is that they have a failure in either the display or printer profile that is causing an inaccurate display under soft proofing. The other main reason why some people don't think soft proofing works is, well, they simply don't know how to soft proof...
Don't get caught up in the "calibration" of your display...you need to concentrate of "profiling" whatever your display is set to.
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Jeff, thanks. What do i need to do to have an "accurate profile of the state of my display"? And how do i use this display profile in the print workflow? I thought I was just "calibrating" my display to 6500 2.2 (with a spyder)...
What you are saying makes sense to me but that's exactly where my question comes from - how do I know my printer profile and display profile are speaking the same language?
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Jeff, thanks. What do i need to do to have an "accurate profile of the state of my display"? And how do i use this display profile in the print workflow? I thought I was just "calibrating" my display to 6500 2.2 (with a spyder)...
When you make a profile of your display, it's used in the OS and fed to color management aware applications like Lightroom and Photoshop.
What you are saying makes sense to me but that's exactly where my question comes from - how do I know my printer profile and display profile are speaking the same language?
They don't speak the same language...the applications use the profiles. The display is used to show you the image, the output profile is used when your image is sent to the printer. In the case of soft proofing, the application modifies the display profile by the output profile.
Really, you are over thinking this stuff. Yes, it's useful to calibrate to a consistent state before profiling, but it's the profiling that is critical for applications to be able to show you what your image really looks like.
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Jeff, thanks. What do i need to do to have an "accurate profile of the state of my display"? And how do i use this display profile in the print workflow? I thought I was just "calibrating" my display to 6500 2.2 (with a spyder)...
What you are saying makes sense to me but that's exactly where my question comes from - how do I know my printer profile and display profile are speaking the same language?
Loosely speaking, display calibration is the process of setting your display to a known standard, e.g. a 6500K white point, gamma curve of 2.2, white and black luminance levels, and - depending on which software you use - equal R, G, and B levels creating a neutral color. The goal of calibration is to create a consistent baseline. Also, accurate calibration is critical for matching displays for multi-monitor or user setups.
The aims of profiling are twofold. First is to refine the calibration. The whitepoint, gamma, and neutrality are adjusted. Additionally, profiling details the overall capabilities of the display. Either a matrix or look-up table (LUT) is created enabling color managed applications such as Lightroom, Photoshop, etc. to calculate what RGB value must be sent to the monitor to produce each color specified in your images.
The main advantage of having accurate display calibration is that the profile need to do less work in correcting the output. All color-munging by the profile comes at the cost of creating artifacts in what you see on-screen. An accurate calibration, particularly when performed in a monitor having high-bit internal LUTs, means less banding and posterization in your view of images.
Your display and printer profiles "communicate" through the color management engine used by your software, be it Adobe, Microsoft, or Apple. The colors in your image are converted into a device-independent color space (translation: a color space where the numbers themselves describe an actual, real world color). These values are fed into your display profile so the output on your screen is as faithful as possible to the image. Likewise, at print time the image colors are converted using the printer profile to produce a print that is as close to the original as possible.
The exact settings used for display calibration are open to (never-ending) debate. Here's my take: We want to see the best possible representation of our images on-screen, with the proviso that there should be correlation to how prints from said images appear. The exact calibration settings used depend on the hardware (monitor and printer) used and our personal color vision. Taking the major settings in turn:
- White point: The standard (in the US particularly) for print viewing is a D50 whitepoint. If you are not viewing your prints under a 5000K light source, all bets are off for screen to print matching with standard printer profiles. (Yes, it is possible to make printer profiles for other viewing conditions; the vast majority are made for D50.) Due to the relative efficiency of how monitors render white and quirks of human vision, most people see a closer visual match between a white on-screen image and a 5000K-illuminated piece of white paper when the monitor is set to a 6500K white point. There is no absolute answer here: compare a white square in Photoshop to a blank sheet of your paper stock in a viewing booth or station. If the on-screen white looks too blue, reduce the white level. One of my colleagues calibrates his screens to 5000K and swears about the "damned blue displays" the rest of us use. When I view images on his screens, I have difficulty getting past the dingy yellow cast. To each his or her own.
- Gamma: The recommendation for a gamma of 2.2 came about because this was close to the average native gamma for most CRT. Given that any changes in gamma from the native value, particularly on panels from a decade or two ago, created opportunity for banding artifacts, calibrating to the native gamma made sense. With LCD screens, it does not make as much difference. Native gamma is, for compatibility with CRTs, close to 2.2, so this still works. If you have a high quality monitor and calibration software that supports it, L* gamma has much to recommend it. The L* curve more closely matches human visual response, creating greater tonal separation where necessary to see image details. L* can create weird banding and crossover artifacts if the monitor hardware is not up to the task. My preference is to try both L* and 2.2, view test images such as this one (http://www.drycreekphoto.com/Learn/Calibration/monitor_sensitivity.html) to check relative performance in shadows and highlights followed by a grayscale ramp (http://www.drycreekphoto.com/Learn/Calibration/monitor_gradient.htm) to look for artifacts. Choose the gamma curve that gives the best performance.
- White luminance: Here's a can 'o worms. Other then a few top-end monitors, most panels show gamut reduction and increased artifacts when set to luminance levels under 130-140 cd/m2. If your print viewing environment is sufficiently bright, running at a luminance of at least 130 improves your view into the image details and prevents time spent correcting image flaws that turn out to be calibration artifacts. Many photographers either do not have dedicated viewing booths or simply hold a print up to their screen using ambient light or a task lamp for illumination. This produces the "my prints are too dark" complaints Andrew noted above. You can either solve this problem by dialing down your screen luminance or using a brighter light for viewing prints.
- Black level: Most monitor calibration software does a decent job of determining the lowest usable black level. Yes, you can obtain deeper blacks, but this comes at the expense of plugged up shadows. For general use, I recommend getting maximum output contrast by setting black to the minimum usable level. Soft proof using the black ink simulation to make sure your shadow details will hold up. If you print to a very low contrast paper, like the newsprint job I should be working on now, dialing the display contrast down can help preview just how much your images will suffer in print and let you adjust accordingly.