Questions Regarding Color Working Space and ppi

[George Tyndall]

The course I am currently takiing for PS CS5 suggests changing the RGB Working Space from the default, Monitor RGB (sRGB-IEC61966-2.1) to Adobe RGB (1998). He also suggests changing the Image Interpolation from Bicubic to Bicubic Sharper.

After changing those preferences in PS, I also changed the Color Working Space preference for the printer to match.

Although the instructor states that the change will result in a larger "gamut," which will look so much better on one's printer, there is NO QUESTION that on my Epson Artisan 50, using quality matte paper and original Epson inks, the quality of the latter is inferior, specifically, there is markely less detail in the model's black hair. Both prints are 7" x 10.5" and 230 ppi.*

Comments, please.

*With regard to ppi, Epson states that, for a quality print, one should not drop below 220 with an inkjet printer, however, a print that I inadvertently made at 100 ppi seems as high quality as those I've made at 220. Another comment please.

[Bob]

Photoshop Color Management can get a bit complicated. It will help if you read this for some background first: http://www.computer-darkroom.com/ps12_colour/ps12_1.htm.

Do you calibrate your monitor? Monitor RGB (sRGB-IEC61966-2.1) suggests that you don't. The Monitor Color setting is not normally used for a color managed workflow with a calibrated monitor. With a calibrated monitor, Adobe RGB is a reasonable working space for print and sRGB is a reasonable working space for video or web work.

Unless you have a set of accurate ICC profiles for your printer and paper combination, it's best to use the option to let the printer manage the color and print the way you were doing it before.

[George Tyndall]

It will help if you read this for some background first....

Thanks for that, Bob. Problem is, I'm stil confused by the following statement:

1. Printer Manage Colors - with this option Photoshop instructs the printer to carry out the conversion between the document color space and the printer vendors preferred color space. Photoshop will not change (convert) the document if this option is selected. This is the most appropriate option when you don't have ICC media profiles for your particular printer/media combination.

2. Photoshop Manages Colors - with this option Photoshop will convert the document to the printer/media profile selected that you have selected in the Printer Profile pop-up. Many desktop printers are now supplied with generic media profiles, but much more accurate prints can be obtained if custom profiles are used. However, for this option to work correctly color management must be switched off in the printer driver.

Since I switched to Adobe RGB (1998) as the instructor suggests, I've repeatedly gotten dialogs stating that there is a conflict between my Working Space and the ICC profile contained in the new file -- AND, as i said, the print quality from the Epson, even if subtle, is clearly not as good. BUT, I do hasten to add that both outputs are overall VERY GOOD, in other words, giving me prints that look identical (but, of course,with less luminosity) to what I am seeing on my HD Samsung TV.

To answer your question, I do not calibrate my monitor/TV but the instructor does with ColorMunki, so, as you've suggested and based on the difference in printed results, I am going to restore my previous settings.

Thanks for still once again sharing your expertise.

[Helen]

Hope you don't mind me asking a question, but I too am confused with this as well.

I calibrate my monitor, but I was under the impression that I should still have "sRGB-IEC61966-2.1" in the RGB Working space, or am I just ignoring my calibration profile when I use this option.

I have read the linked article previously and I do pick up more info each time I read it, but I also confuse myself as well.

[Bob]

I calibrate my monitor, but I was under the impression that I should still have "sRGB-IEC61966-2.1" in the RGB Working space, or am I just ignoring my calibration profile when I use this option.

No, you aren't ignoring your calibration profile using that option. The working space and the monitor profile are independent and serve two different purposes.

When you calibrate your monitor, you are actually doing two things. First, you are literally calibrating the monitor. That is, you are setting the operational settings of the monitor and video card to a standardized state where you establish the color temperature, the gamma to be used, the black and white points, and so forth. The second thing you are doing is establishing a profile that describes how the monitor reproduces color. Known colors values are sent to the monitor and the colors actually displayed are measured to determine how they differ from what they should be. Both the calibration data and profile data are saved in the monitor's ICC profile. The calibration data is loaded into the video card's look up table (LUT) at startup by a LUT loader. The profile data will be used by color management aware applications, such as Photoshop, to adjust the color values that are sent to the monitor so that the displayed colors will more accurately represent the actual color values.

The working color space, on the other hand, doesn't calibrate anything or describe how a device handles color. It has a different purpose. It determines how the numerical values that represent a color are interpreted. In RGB, colors are defined by a triplet of numbers -- one for the red value, one for the green value, and one for the blue value. But, a number alone isn't enough. Which specific color is associated with a specific value. Adobe RGB 1999 and sRGB-IEC61966-2.1 are device independent absolute color spaces. That is colors in the space are colorimetrically defined without reference to external factors. They provide the framework whereby we can say absolutely what color corresponds to which number and which colors are in the color space and which are outside the color space.

sRGB was originally intended to represent the colors that could be displayed on a typical CRT of the day, while Adobe RGB was intended to represent the colors that could be printed on the cmyk printers of the day.

sRGB is a good choice as a working space if you are mainly making photos for display on a computer monitor, on a web page, making a video, or sending them off to a commercial printer to make prints. Adobe RGB is a good choice if you are making your own prints on a photo quality inkjet printer -- especially if your photos contain areas of highly saturated colors.

[Helen]

Thanks Bob, that info has certainly made it all a lot clearer.
It has finally clicked in my brain.

[Bob]

Thanks for that, Bob. Problem is, I'm stil confused by the following statement:

1. Printer Manage Colors - with this option Photoshop instructs the printer to carry out the conversion between the document color space and the printer vendors preferred color space. Photoshop will not change (convert) the document if this option is selected. This is the most appropriate option when you don't have ICC media profiles for your particular printer/media combination.

2. Photoshop Manages Colors - with this option Photoshop will convert the document to the printer/media profile selected that you have selected in the Printer Profile pop-up. Many desktop printers are now supplied with generic media profiles, but much more accurate prints can be obtained if custom profiles are used. However, for this option to work correctly color management must be switched off in the printer driver.

Color management for printers can be confusing.

Printer profiles can be created to describe the way the printer reproduces colors. Those profiles can then be used to adjust the color values in the image to compensate for the way the printer reproduces them. Unlike monitors that can get along with a single profile, printer profiles depend on additional factors such as the type of ink being used and the paper used for printing. You will need a specific profile for each combination of ink and paper that you use with that printer. Printers designed for printing photos generally come with a set of generic profiles that correspond to the standard inks for that model and the manufacturer's brand of photo printing papers.

Printers, by default, do their own color management conversions based on the settings you choose in the printer driver. They generally do a reasonably good job. If you want the printer to continue to do the conversion, choose the "Printer manages color" option. Photoshop will send the image color values to the printer unchanged along with the document profile used by the image and the printer will do the rest.

If you want more control over the conversion, you can turn off the printer conversion in the printer driver and then have Photoshop to do the conversion by selecting the "Photoshop manages color" option. If you do that you will need to select the appropriate printer icc profile yourself. For best results using this option, you really should have custom printer profiles made for the printer/ink/paper combinations that you will be using. This option requires that you know and understand more more about color management and what the various rendering intents and options do.

[Bob]

*With regard to ppi, Epson states that, for a quality print, one should not drop below 220 with an inkjet printer, however, a print that I inadvertently made at 100 ppi seems as high quality as those I've made at 220. Another comment please.

Almost missed this question. Simple question, not so simple to answer.

A lot of factors go into how ppi will affect print quality including the viewing distance, the type of paper, the content of the image, the technology (laser vs inkjet, for example), and even your own visual acuity. For normal handheld prints on glossy paper printed on a good quality photo inkjet printer, around 300 ppi is virtually indistinguishable from a lab printed photograph. Holding every thing else constant, reducing the ppi will lower the quality. You'll start losing fine detail and the photo will appear softer or less sharp and possibly grainier. This will be more noticible on images that are very sharp and contain fine linear detail that would smear out and possibly disappear or reveal stairstepping due to pixelation. However, even around 200 ppi the print will be near photographic quality. Prints on matte paper will resolve less detail than prints on glossy paper and you will be able to get by with lower ppi values before you notice the difference. You can go even lower for prints that are placed on a wall and viewed from a distance. 150 ppi may look good from a few feet away and those large poster size prints that are viewed from across the room may look good at 100 ppi. Billboards have been printed much less than that.

Since I switched to Adobe RGB (1998) as the instructor suggests, I've repeatedly gotten dialogs stating that there is a conflict between my Working Space and the ICC profile contained in the new file

In the color settings dialog, the color management policies section determines the default action that will occur when you open a file containing an embedded profile that is different from the default working color space. There are also check boxes to allow a warning message to pop up informing you of the mismatch and give you an option to choose an action other than the default. You have those warning boxes checked. It's not a conflict, it's asking you how you want to handle the mismatch. Normally you would want to preserve the embedded profile. In the case of a missing profile, I would recommend that you don't uncheck the box unless your default working space is sRGB. With a missing profile, the image will be unmanaged which would result in a profile not being embedded when you save, but you will be viewing in the default working color space. If that is Adobe RGB, your color values will not be displayed properly -- unprofiled images are implicitly sRGB. It's best to pop up the message in that case and assign the sRGB profile.

edit: forgot to mention that when you use the monitor color settings option you are effectively bypassing color management and working with a non-color managed workflow. You also won't be able to check the warning box for missing profile in that case since it doesn't really apply.

[George Tyndall]

Color management for printers can be confusing. ....

Thanks for that very clear and comprehensive explanation, Bob.

BTW, before I ask still another question, I want to state that I have never had a problem with my printed images differing from what I see on my monitor, with either PSE4 or PSE7. My settings have always been as follows: 1) PSE>Edit>Color Settings>Optimize for Computer Screen (sRGB) 2) Epson R340 and Artisan 50 printer settings: Paper>Premium Presentation Matte, Heavyweight; Quality>Photo RPM (Max dpi); High Speed On; Black/Grayscale Off; Edge Smoothing Off; Color Management>Fix Photo>Auto Correct>Digital Correction>Smooth Skin. (Most of my work consists of portraits made in a studio.)

When I installed PS CS5, I used the same settings, again with excellent results.

The one and only reason for my inquiry regarding this topic is that, in the introductory course that I am taking regarding PS CS5, the highly-regarded instructor (who is on the faculty at Brooks in Santa Barbara), states early in his presentation that it is VERY IMPORTANT, if one's output will consist mostly of prints, to calibrate one's equipment (monitor, printer, paper and projector) with a device such as a ColorMunki and then choose Adobe RGB (1998) in the PS Color Management dialog (or ProPhoto RGB if one also uses Lightroom).

But as I've stated, the output that I am getting from my Artisan 50 looks better (better details in the shadows) with the settings that I've always used than with the Adobe RGB (1998) settings. I'm assuming that the reason is that I am not following his advice to calibrate my equipment.

If you are not yet weary of discussing this topic, please help me to better understand the method that I've been using and also add a comment whether I would see even better printed output if I followed his method of calibrating my equipment. Before you reply , please be aware that 1) Most of my output consists NOT of prints but of SD and Blu-ray DVDs, and I am very happy with the quality that PRE has been giving me with these using the settngs that I mentioned above 2) although I am stil producing some of my creations with the monitors mentioned in my signature, most of my work is now being done on a 52-inch LCD HDTV (which I'm not sure can be calibrated even if I wanted to).

[Bob]

The one and only reason for my inquiry regarding this topic is that, in the introductory course that I am taking regarding PS CS5, the highly-regarded instructor (who is on the faculty at Brooks in Santa Barbara), states early in his presentation that it is VERY IMPORTANT, if one's output will consist mostly of prints, to calibrate one's equipment (monitor, printer, paper and projector) with a device such as a ColorMunki and then choose Adobe RGB (1998) in the PS Color Management dialog (or ProPhoto RGB if one also uses Lightroom).

I dislike blanket statements like that with regard to setting the default color space. There are advantages and disadvantages associated with each color space choice and a wider gamut color space isn't always the best choice.

Adobe RGB is wider than sRGB, but very often the range of colors in a photograph will fall entirely within the sRGB color space and sRGB will be all you need. That's because the additional areas are mainly in the more saturated intensities of colors. It also varies by luminosity. Adobe RGB extends into the greens in the shadow areas, green/ cyans in the midtones, and the highlight areas can additionally extend into the yellow/magentas. That makes Adobe RGB theoretically better for landscape photography and sunsets when you have strong saturated colors in those ranges. But, can you even get those color areas in your photos? Even if you can, there is a downside. The wider range of colors is expressed in the same numerical range as sRGB. That means that working in Adobe RGB can introduce posterization in areas where you have subtle continuous tone gradations that would not be posterized had you used sRGB. You can minimize that by working in a greater color depth. If you are going to use Adobe RBG as your working space, you really should use 16 bit mode.

As for getting those colors, on the camera side, you would need to use RAW format or capture to Adobe RGB. Not that many have an Adobe RGB setting. If you are using standard sRGB jpegs, opening them up and converting to Adobe RGB buys you nothing. You can't add colors that aren't there. On the output side, you can save jpegs with an embedded Adobe RGB profile, but jpegs are 8 bit, not 16 bit. And, very little software and devices will recognize an embedded profile and work correctly with a jpg that isn't sRGB. Likewise with the printer, except for a few very high end printers, they are 8 bit devices. Also, your inkjet printers may not be capable of printing the full Adobe RGB range. In some areas, the printer may be able to exceed the range, in others it can't output them at all.

Just about everything is currently designed around an sRGB workflow. HP and Microsoft got together back in the early PC days and established that. The basic idea being that if all devices were natively sRGB, then the user and the software would not have to worry about the details of color management. Printers, monitors, the pc hardware, even your hdtv essentially use sRGB. If you use an sRGB workflow, either explicitly or implied, things are a lot easier. If you use an Adobe RGB workflow you will need to know something about color management workflow and how color workspaces are transformed from one to another.

The problem with Microsoft's implementation is that it's an uncalibrated workflow so the sRGB space is not based on an absolute color space and color can vary from one system to another or from one component to another. The difference may be subtle if you're lucky or way off if you're not. That's why calibration is so important if you need accurate consistant color. However, if you calibrate your monitor, you may also need to calibrate your printer and develop profile or you may lose that match between screen and print.