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ben egbert wrote:
I have sometimes used 120 for brightness which helps for printing, but I had a custom print profile made that matches a screen brightness of 150.
A printer profile has two roles in a color managed workflow: 1) fitting the file values to the gamut of the printer's paper and ink, taking into accout mechanical varialbes, and; 2) softproofing on the monitor to simulate how the image will look on the print.
The limiting factor when printing is the gamut the paper/ink create. It is what it is and it is, is better on some printers than others and is a DIFFERENT SHAPE than the gamut of RGB monitors.
What do I mean by shape? Color managed color is mathematically modeled and manipulated on the axes of the Lab coordinate system. The gamut of Lab was defined with testing in the 1930s as the range of color a "standard observer" (i.e., average human with no color vison defects) can detect.
The ColorSync utility in OSX allows comparision of gamuts as 3D wireframes. Here's the comparison of my iMac's calibration profile and the profile for HP glossy paper on the 8/C printer next to it, seen from the "top" and "bottom" of the color space along the "L" axis:
The areas where the screen gamut is hanging out are colors the monitor can display with more saturation than printer can match. The yellows and greens hanging outside the monitor's gamut are colors the printer can reproduce "better" than you'll ever see them on your screen — in absolute terms of color you can see.
That physical difference and the fact that the printer can reproduce some colors better than a monitor is the reason you don't want your default monitor calibration to match the printer. Note I said monitor match the print.
The advantage of a wide gamut monitor is that it can display more of the printer's gamut accurately. For example here's the same printer profile compared to AdobeRGB in 3D from the top and bottom of the L axis (north and south poles of 3D colorspace):
There are still a few colors the printer can print with more saturation than AdobeRGB can display accurately.
Most starting out think in opposite terms and come to FM asking: "How can I get my printer to match my screen?" The answer is, "You can't". The printer's gamut is what it is. You can't increase the max saturation of the color it will print, you are just messing with the balance and rendering of the less than 100% percentage of CYMK ink the printer can lay down on the paper.
If you have a less expensive monitor or laptop you aren't seeing how the file will look when printed because of the limits of the monitor and are more likely to make poor, uninformed decisions simply because you are flying in a cloud by instruments.
What calibrating your monitor does is balance the RGB pixels so 255,255,255 and 128,128,128 and 16,16,16 all look neutral. But neutral perceptually is a moving target because the brain adapts to expectations. If you calibrate the monitor to a D50 / 5000°K white point, which was common in graphic arts in the 90s it the WB and color will look the same as with a D65 white point because your brain will adapt your color perception. But if you were to take a file edited on a D50 monitor and display it on a D65 calibrated one then will look different. That was the source of the Mac vs PC debates in the early days. Macs used a "paper white" 5000°K white point, while PC monitors where usually uncalibrated with a native WP of 9000°K. The gamma on early Mac screens was adjusted for 1.8 vs 2.2 on a PC.
What sorted things out was everyone agreeing to the same standards for viewing files on screen: D65 with 2.2 gamma.
What sorted things out in commercial offset publishing was all printers and color separators proofing using SWOP or other standard inks and paper and adjusting press profiles from that standard baseline
But there is no standard baseline for digital printing because the gamut of each printer is different and it changes everytime a different paper stock is used.
If a printer is sent a 255,0,0 RGB file value the color management engine in the printer (printer manages color) or Photoshop will convert it to M=100% + Y=100%. How that looks will vary between printers because the use different pigments. So one part of the conversion is mapping the extremes of the file values to the limits of the printer's gamut.
The other part is getting the less saturated colors looking "perceptually" correct. If you have a 128,128,128 gray in the file you calibrate your montitor to make it look gray. What the printer profiling process does is print that 128,128.128 gray and figure out why in isn't being printed as gray when color manangement is turned off.
If you use the "North America Web / Internet" selection in the color setting preferences Photoshop inserts "SWOP Web Coated" as the default CYMK space. If you go to the color picker and enter 128,128,128 as the RGB coordinates you'll see 52% C, 43% M, 43% Y, 8% K as the "recipe" for "SWOP middle Gray". Note there is more Cyan required than Magenta or Yellow to achieve "Gray Balance".
Now go back to color setting and change the CYMK default to "US Sheefeet Coated" and then look at the CYMK equivalents for 128,128,128 RGB gray. They change to 48%, 37%, 37%, 5%. The balance of C vs Y/M is still unequal and the values are lower meaning less ink is needed to create the same shade gray on sheetfed vs web press.
The difference? The paper brightness and absorption characteristics. What is assumed, but not obvious with those presets is the the papers and inks being used to print the targets which created those profiles where SWOP and Sheetfed standard papers as defined in printing industry specs. It was the establishment of standards like SWOP that allowed an advertisement for Coke to wind up looking "Coke Red" regardless of the press it was printed on.
All of this is obvious to me because I worked in printing and started dealing with color management in the mid-70s long before digital. When you print you need to manage the color backwards from the press.
First you print a target with known values for max 100% CYMK — as much ink as the printer can put on the paper and without dripping off onto the floor — neutral R=G=B — and lighter color combinations.
The printed sheet is then evaluated with a colorimeter. The 128,128,128 RGB patch will look too red and too light in tone because of the pigment impurities so the profile creation software adds more Cyan and a bit of Black to the recipe for CYMK middle gray. Since the paper and inks are different for web vs sheetfed the recipe for gray and all the other less than max % colors wind up different.
The profiling process is the same for ink jet and photo printers. When you get a custom profile make you are asked to print a standard target which is sent off and read on the same type of analyze we used at the printing plant to profile our large presses.
The printer profile is the road map for shifting the colors. Printing 255 Red as 100% Y+M is pretty much a no brainer on any printer and paper. Were the profile is critical and varies with paper is getting the neutral grays and less saturated skintones looking the same on the print as on the screen PERCEPTUALLY.
When you put a print next to a monitor and compare them the will never match in absolute terms in the most saturated colors. But go back up and look at the 3D wireframes. See how most of the colors are overlapping? The overlap in the wireframe render means they are the same in both gamut and don't change much between screen and print.
So if you have a photo of a woman in a yellow dress and print it the face will look similar on print and screen but you should expect the color of the dress to change. Why? It is physically impossible for the printer to create a purple that is as saturated and bright as your RGB monitor
Adobe, understanding that monitors can't match printers created "Soft Proofing" view mode to allow the user to simulate how the colors and contrast will change when an image is printed. It is done by inserting the printer's calibration profile the loop between the RGB values in the file and the RBG calibration profile making the image look perceptually correct on the monitor's gamut.
Here's an image that will not print to match my screen:
When I activate soft proofing, select my printer profile for the paper I plan to use and turn on the "out of gamut" warning I see this on screen:
What that tells me, because I understand how to interpret it, is that the face will print OK and not change because all the colors that are not grayed out by the out of gamut warning are the same in absolute terms in the printer and screen gamut.
What would happen if I soft proofed on a wider gamut monitor? It wouldn't change the fact that the purple background looks duller on the screen because that's due to what the inks can print. The only difference is that the monitor will be able to display that fact more accurately. I'd see the same color shift but less of it would be grayed out by the "out of gamut warning" which tells me what areas my monitor isn't simulating accurately.
What will happen when I print the file? Photoshop will send 255,0,255 file values in the purples and the printer will put as much C + M ink there as it can but the results will only look about as saturated as the screen will look if I were to reduce saturation in the colors that triggered the the out of gamut warning during soft proofing.
The printer can't match the normal calibrated screen gamut because it can't physically create the same purples. What injecting the printer profile does is reduce the output of the RGB drivers on the monitor to degrade the image to look as "bad" as the printed image will look.
Why do that? Because the point of the soft proofing exercise isn't to make the image look it's best on screen it is to PREDICT THE OUTCOME OF THE PRINTING WITHOUT NEEDING TO WASTE INK AND PAPER.
At best soft proofing is a rough simulation of the actual results. As with most situations where actual results don't match expectations your brain will learn to corollate what is seen on screen in soft proofing mode in the out of gamut warning areas with how much those areas will shift in color when printed.
But more importantly the soft proofing process changes the CONTRAST of the screen to simulate the lower contrast seen when the image is printed. You can't increase the color saturation of inks in the printer but you can change the contrast within the file to improve its appearance PERCEPTUALLY by tweeking the contrast range of the file.
Again because I managed reproduction workflows as my profession I'm aware of what makes images change perceptually when printed and what can be done to fix it. The change is due to the difference in overall contrast between white and black. The white on paper doesn't seen as bright as the white on a monitor and the blacks don't seem as dark because there are physical limits to how much CYMK can be stacked on top of the paper.
You can't control the white on the paper except by changing types or the max density the printer can print to change the appearance of the print percepyutally.
The variable that can be changed? The mid-tone contrast.
Take any file you have printed previously and think turned out too dark per comparison with the screen.
Open it in Levels then move the middle slider left to 1.20
The print should now better match the screen. The problem wasn't the color gamut in a photo like that because all the colors seen on screen fit into the printer's color gamut. The problem was the printer has less inherent contrast on the screen.
The take away? You need to edit contrast differently for printing than display on screen. After getting the highlight and shadow values correct per detail seen you need to adjust the mid tones until they "look right" when printed.
Next take the file that looks good on screen and soft proof it. You should see the image change and show the same too dark results you encountered when printing the file. Looking at the file in soft proof mode open Levels, adjust the middle slider until it looks "right" on the screen. Save it as a copy file and print it. The print should better match what is seen on screen with soft proofing off.
If you take the time to do that Ben you'll may realize you shouldn't be changing the brightness level of the base calibration of your monitor to match the contrast of your print results you should calibrate the screen so the image looks normal and then SOFT PROOF TO SIMULATE HOW THE CONTRAST WILL CHANGE WHEN PRINTED. Then while in soft proofing mode make a midtone tweek, sharpen, etc. then save as a new file with the suffix "_printer".
For any file you'll wind up with four copies:
1) The RAW
2) A "master edit" .PSD copy in 16-bit ProPhoto, uncropped, unsharpened with all your dodging / burning, etc. adjustments.
3) A screen resized and converted to 8-bit sRBG first, then tweeked and sharpened to optimize appearance.
4) A print copy resized and converted to how you send the file to the printer (e.g. Level 10 JPG) tweeked IN SOFT PROOFING MODE USING PRINTER PROFILE and sharpened to optimize appearance.
When I print in different sizes I start with the master edit in step 2, resize to the print dimensions x output resolution (e.g. 2400 x 3000 for 300ppi 8 x 10, 1200 x 1800 for 4 x 6) then sharpen and do the final tweeks in soft proofing.
I edit different size prints individually because I know print size and viewing distance affects viewer perception of them. That's the piece of the reproduction puzzle I take for granted due to my background that others miss.
Reproducing an image is for the most part an exercise in "faking it to make it seem real". What looks real on a print is different than what looks real by eye because the brain can't interpret the clues the same way. Varibables like image size and viewing distance are not factors when looking at a landscape in person but they are when looking at a photograph of the landscape.
The learning curve in reproduction is discovering what technical factors, such as shifting of the mid-tone and sharpening, are needed to convert what the camera captured into what the viewer will be able to see at that viewing distance from the print. Beyond reading distance the brain shifts gears and relies less on texture on the front of objects and more on their overall contrasting shape with the background to identify them.
If you look at a photo of a forest and a sailboat on the ocean from across the room you'll identify and relate to the sailboat faster because to has large contrasting geometric shapes. That dynamic is why this pretty picture works. The contrast of the V tree line and the ^ mountains with the sky create geometric shapes that are easily seen and processed.
But stand up and walk across the room and look at it or apply the Guassian blur test I did on your other images. How does it work then? That will predict how well it will work printed 30 x 40 and hung over the fireplace...
But all things consider nowadays it's simpler and looks better to just hang a wide screen TV over the fireplace and run a slideshow on it. Then you don't need to worry about the print matching the monitor.
Edited on Jul 30, 2012 at 02:16 PM · View previous versions