Paper Surface Affects Color

I recently made a profile for Howard Linen by Neenah. I profiled it through a Creo Spire workflow to a Xerox 6060. Even though the paper is meant for double sided printing the fibers of the paper are different on both sides. This causes the toner to lay down differently on each side. This affects color. A couple of notes in case you are not acostomed to profiling through Creo. You have to build a new calibration for your media. then when you send a CMYK profiling testchart through the RIP make sure you send it through a “Direct” pathway. This will bypass any color management – even though there is a choice for ICC profile. Once the profile is built you have to import it back into the RIP. This is not an issue if you have a .icc extension. I taught a course for X-Rite and Creo about a year and half ago all about this and wonder how manyare actually building profiles. John Gilbert would know.

Display Calibration at it’s Best

This is a screen capture of X-Rite’s i1 Match Software. I used my i1 Pro Spectrophotometer to build a calibration and profile for the new 24″ iMac. The default white point was right at 6500 Kelvin and the resultant calibration yielded a perfect 120.0 cd/m2. This is rare. Sometime you get lucky. Other iMac’s I have calibrated don’t give me the same results – that’s not necessarily bad – except one of the best ways to get multiple displays to look similar is to have similar luminance say +/- 2 candelas.

Color Management for Photographers

Do you wonder why the photos you print don’t match how they appear on screen? Learn how to color manage your system from capture to print in this short, intensive workshop. From basics of digital color, discover how to use a color management system including software & hardware. Topics include: limitations of color gamuts, color settings, calibration and profiling of a LCD display & profiling a media on the supplied photo quality inkjet printers. Prior experience in digital photography & working knowledge of computers & Photoshop CS , CS 2 or 3 required. Bring 5 digital images to 1st class meeting. Note Printing elective for Professional Certificate in Photography. prerequisite: Intermediate Photography in the Digital Age (ART 40440) or equivalent experience. For more info. or to discuss prerequisites, call (858) 964-1051 or ahl@ucsd.edu.

IN-CLASS
Instructor: Marc Aguilera
Section: 079251 Course No. ART-40402
Time/Date: W 6:30-9:30 p.m., Sep. 22-Oct. 27 (6 mtgs.)
Location: Rm. 134, UCSD Extension Complex
Credit: 2 units in Art
Fee: $325 No refunds after: Sep. 27 (da/amn)
No visitors permitted. Early enrollment advised.

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Projector Profile Results

examples from my latest blog post on the hp pro photography blog

results of projector profiling with i1 Pro and i1 Match

Reds and Warm Tones from projector profiling with i1 Pro and i1 Match.

Result from projector profiling with i1 Pro and i1 Match

Skin Tones from projector profiling with i1 Pro

SWOP – Quickly Defined

SWOP is the Specification for Web Offset Publications and more information can be found at swop.org or the idealliance.org. It is the main specification used by press house in the united states.

Farnsworth Munsell 100 Hue test

Have you taken this test? If not you should. I have taken it three times and have never got a perfect score. I once administered this test to a woman at the SIGGRAPH show in San Diego and she scored perfect many times in a row. She was amazing at seeing color difference. You can take the test online but that’s not as much fun. It’s better to take the test in person. The test is used by the government and industries where determining color difference is really important in a particular job function and it has been used for over 40 years. It consists of 4 trays containing 85 caps – your job is to put the colors that space the spectrum in order of transition from one hue to another. The test must be administered under a daylight balanced light booth as pictured here. If you haven’t taken it or you want to see if your employees are color deficient in a particular area I suggest you get the test.

Inside an ICC Profile (Part 1)

Profiles are a mystery to most users. Even for me the first few years in color management, I had no idea really what was in an ICC profile. Essentially when I learned what was inside a profile it made for easier understanding of how profiles actually work. While this information is not necessary for an ICC workflow it sure helps with comprehending a general framework of how and why an ICC aware workflow does it’s magic.

According to Understanding Color Management by Abhay Sharma, a profile is “a data file describing the color characteristics of an imaging device”. Profiles are made for scanners, digital cameras, displays, and print devices. There are even profiles for “non-devices” such as a color space profile. Profiles usually have an extension of .icc or .icm. Profiles are used to translate color into or out of one color space to another. An example can be sRGB from your digital camera to the default profile for your display. Another way to explain this is to call upon the Adobe® terminology of source to destination color.

Profiles have two main parts: tags and headers. There are many tags to describe different functions a profile has. There is a quality setting tag. Sometimes you need to fix a particular tag in order to troubleshoot your ICC workflow. The ICC (International Color Consortium) regulates the structure and contents of profiles.  The header usually contains information about device type, i.e. Epson Scanner, Apple Cinema Display, hp Designjet Printer. The tags are the body of the profile and contain all the working data. Headers are standardized and contain a fixed number of items. Tags are device dependent and the number of tags vary according to class and profiling software. Display profiles have different tags compared to print profiles. Scanner profiles have different tags compared to “non-device” profiles like Adobe RGB. If you run OS X you can double click on a profile and it will oped colorsync and you can view header and tag information. There are also “profile inspector” tools available to view and even edit the contents of a profile available for both Mac and Windows. LUT’s are Look Up Tables and are found in ICC profiles and are used to do image conversions.

CMM Type

One of the headers is the CMM type. CMM is the Color Management Module and is the color engine that does the color conversion on an image. The main role of the CMM is to convert the image data from one color space to another using all of the information contained in the profile. CMM’s come from Apple, Adobe. and Kodak as well as a few others. The Adobe ACE (Adobe Color engine) is cross platform and is the most common CMM used today. Most CMM’s behave the same way however you can test the effect of a CMM by changing it in a profile editor or in an ICC aware application.

Profile Class

The profile class header tells us what type of profile it, such as scanner, monitor, printer, etc. There are seven profile classes : display (mntr), input (scnr), output (prtr), device link (link), color space (spac), abstract (abst), and named color (nmcl). Typically profile class tells the type of tags that will be present in a profile and without it applications will not know what to expect. We can easily expect what a display, input, or output profile is used for. Device link profiles are one profile that links two profiles together. Most Device link profiles are CMYK to CMYK and are used to shortcut a color conversion. Device link profiles are very effective dealing with issues converting from CMYK to CMYK especially in areas like black generation. Color space profiles examples are Generic Lab and Generic XYZ profiles and are used to convert images into or out of a device independent space. Abstract profiles are used for special purposes like storing image edits and finally named color profiles are used to support color information from named color systems like PANTONE.

Data Color Space and PCS

Data Color Space refers to the device color space like RGB or CMYK. PCS refers to Profile Connection Space and is usually XYZ or LAB. Profiles usually but not always work in both directions, from the Data Color Space to the PCS or from the PCS to the Data Color Space. Another way to look at it From RGB to LAB and from LAB to RGB, from CMYK to LAB and from LAB to CMYK. Because printer profiles can both be RGB or CMYK when you look at the Data Color Space header you can tell if the profile is treating the printer as an RGB or CMYK device.

Next post we will focus on Flags, Rendering Intent, PCS Illuminant, and more.

Display Calibration

Originally uploaded by colorcritical

Question from a Color Control Freak:

I’m interested in purchasing a Monitor Calibrator for my Vista OS. Which monitor calibrator would you recommend? Also, how do I know if the monitor calibrator is compatible with my HP 2009m Monitor? I really don’t understand how a monitor calibrator works and how it can alter the monitor colors. Is it interacting with the NVIDIA video card?

A: I like the i1 Display colorimeter by X-Rite at xritephoto.com. A monitor calibrator works by way of software – hardware interaction. The software resets the data table called a LUT (Look Up Table) sent by your video card to your display. When variables are set like Luminance, Gamma, White Point by the software (usually automatically if using an automatic mode or manually in an advanced mode) with the the aid of the colorimeter will “calibrate” your display by altering the LUT to hit the target variables. You will aid this by setting brightness, contrast, and RGB levels on your display (if you have them). After calibration the software then builds an ICC profile that Vista will use in the OS as well as any other ICC aware applications like all of the Adobe® Photoshop™. Go for it – it will make your images look much more real and true to the original intended color values when captured.

ICC Profile Use in CSS3

There will come a day when most of our OS, applications, devices, and browser experiences are color managed. Right now, we are close in some respects but still pretty far in other respects. If you read my prior post on browser compatibility, you found out that with respect to images, they should be embedded with sRGB, but that only helps if your viewing the images on a browser that supports embedded profiles (otherwise the display profile is used as source).

Let’s say we were talking about non image elements, like gray backgrounds or orange headers. How should those elements be color managed, especially if your designer is using Photoshop for conceptual layout? If the web designer uses sRGB as the “Working Space” as he/she is supposed to do, what happens at the level of the Web Producer.

The Web Producer does the splicing of the PS file and makes PNG or GIF files out of the individual elements or he codes directly the hex values into CSS. However, one can not embed a profile into a PNG or GIF. This is where CSS3 comes in. CSS3 will allow the Web Producer to set the color profile for the entire coded page, in this case sRGB. That way when the designer and the producer compare the published beta site and the Photoshop preview the two match (of course right now only in Safari).

It will be great day when all modern browsers use embedded profiles and CSS3 becomes a common standard. If your looking for a fantastic tutorial on the subject check out gballard.net.

Browser Color Management

In response to a post by Jason Santa Maria http://www.jasonsantamaria.com/archive/2007/12/12/gamma_gamma_hey.php

Wow – so many different opinions on this topic. Reading some of the above responses I realize more and more just how important this topic is to the design community. Our agency is completely color managed and I teach this stuff for a living for X-rite, the Owner of Pantone and the i1 Spectrophotometer and Colorimeter. Here is my take on all of it. Before we begin – color is and will always be subjected to the individual observer and your viewing conditions – geeky I know, but it had to be said.

1. All devices produce color diferently (we color geek types call it ‘device dependent color’), even the same device from the same manufacturer next to each other will look slightly different. This is hell.

All applications treat color differently – Mac OS X apps built using Aqua, i.e Mail, Preview, Safari, and iPhoto all use the default display profile and recognize embedded profiles. Windows applications like Picture Viewer and Outlook don’t use a color management engine. Adobe Applications all have a common color architecture and if you synch working spaces will all look the same – but only in the application. IE 7 has an color management setting however the user has to enable it, and the current release of Firefox does not include a color engine. So no matter what, if you plan to implement a color managed workflow your images will look right in Safari but wrong in everything else. (I am not sure about Opera). Finally, if your display is not calibrated and profiled you will have even more trouble – so no matter what it’s best to at least have a calibrated and profiled display. The questions then becomes one of application implementation.

2. Color measuring your display is crucial if you want consistent appearance. If you do not, you’re experimenting with color rather than managing it. All of our displays (5 Mac – 2 Win) are all calibrated with a sprectrophotometer to the same settings – D65 (6500 Degrees Kelvin), Gamma 2.2, and 130 cd/m2 Luminance. When we share files they all appear similar (taken into consideration individual viewing conditions) – regardless of platform. We run Mac OS 10.4 (Design) and Windows XP (Web Production). We all share the same color settings file (.CSF) in our Adobe Apps. sRGB is the Working Space for Web work and Adobe RGB for Print. When a designer prepares an image for the web we like most “save for web” via image ready and embed the icc profile when we really need to match colors and don’t embed when it’s not as crucial. We then brief the client on real world expectations based on Browser implementations and uncalibrated displays.

3. When we embed sRGB it is only is useful for Safari (by default) since Safari has color management enabled by default. It does not help us with Firefox, unless you’re running Firefox 3 Alpha 7 and you run gfx.color_management.enabled to true (via about:config) * How lame is this? Very Lame Indeed!

Conclusions and thoughts:

The idea of ICC (International Color Consortium – http://www.color.org) is still somewhat young in it’s discipline. It was written to be open in terms of implementation, meaning the OS, Applications, and Devices use profiles differently or not at all. This makes it a nightmare for everyone. Apple at least has taken a huge step forward with Colorsync and Aqua and Windows Vista has a new color management system called WCS (Windows Color System) but is has been slow to implement fully. This is the current state of affairs with this stuff. If you want any control you have to give up some and live within the limitations of this imperfect discipline. I would rather we all follow an imperfect standard rather than try to invent a new one. It really comes down to setting expectations within your devices and with the client.

Final thoughts:

We have color issues – but they are minor – most of the time we are spot on. We are Pro-ICC and I recommend all designers and photographers follow. If you decide to go this route you should do the following:

1. Calibrate your display to a standard, i.e D65, G 2.2, Luminance 120 cd/m2 – recalibrate at least once a quarter.

2. Use sRGB as a working space (for the web) and make sure all your applications do this same (although this can be challenge for some applications).

3. When you save your images embed sRGB – in the short term they wont look right in IE 7 and Firefox but there will come a time soon when all of the major browsers will have color management turned on as the default, like Safari.

Reading Real World Color Management by Peachpit Press is great but I fear too much for most designer. Take a seminar. Xrite and I will be launching a seminar series in March and we will discuss many of these issues. Check out http://www.xrite.com or contact me directly at http://www.encompus.com