WHAT YOU CAN LEARN AND WHAT YOU SHOULD KNOW
Can I achieve consistent color across different devices and technologies?
Yes, we can achieve consistent color result across different printer and technologies. We will teach you the procedure in order to have any printing device match the color of another printing device.
What is a Colorspace?
Three attributes provide information to map visible color in a 3D space, Hue, Saturation and Lightness. Albert Munsell is credited as a pioneer of three-dimensional color space descriptions, inventor of the first 3D color space HVC or Hue, Value (lightness) and Chroma. There are many different types of color spaces that resemble Munsell’s designs. Basically, a color space based on hue, chroma, and lightness uses cylindrical coordinates. Lightness is the center vertical axis and saturation is the horizontal axis that extends from the lightness axis. Hue is the angle at which the saturation axis moves from Red 0° to Yellow 90° then to green at 180° and finally blue at 270° from the lightness axis. Color can be mapped just like a specific address on GPS can be mapped. Around the center of the cylinder lie vibrant, pure hues. As the hues mix together towards the center, they become less pure and lose Chroma. On the vertical axis, colors of different hue and saturation become lighter or darker. The lightness extremes of white and black lie at the “poles.” And at the center of it all lies neutral grays where white, black, and all colors meet and mix together.
What is the Lab Color space?
In 1945 Richard Hunter while working for the Bureau of Standards developed a new 3D color space called Lab. Then in 1976 the CIE developed their own CIE L*a*b* which is the most widely used color space today. When a color is expressed in CIE L*a*b*, L* defines lightness; a* denotes the red/green value; and b* the yellow/blue value. In many ways, this color space resembles three-dimensional color spaces like Munsell’s HVC.
How does color Management work and what is the difference between Standardization (G7 and ISO Norm 12647-2 / 12647-3) and Characterization (ICC Profile and other form of profile generation).
“The difference between calibration and characterization is that when you calibrate a piece of hardware, you bring its behavior into compliance with a chosen specification whereas when you characterize a piece of hardware, you only describe its behavior.”
G7 and ISO Norm 12647-2 / 12647-3 are calibration Processes which take an offset press to print according to a Norm; taking into account Standard substrates (Gloss, Matte, Uncoated, Newsprint and Uncoated Yellowish) each substrate has a different Colorimetric Lab value for paper, Primaries CMYK and for Overprints RGB as well as a Standard Tone Reproduction Curve (TRC) for each. The General Idea of Standardizing (Calibrating) an Offset press is that if your ink and paper comply with the Norm (G7 and ISO Norm 12647-2 / 12647-3) and your dot gain also complies with the norm you can use a single ICC profile (ISO Coated V2 Fogra 39L or Gracol 2006 for example) for various presses and your entire offset printing process, even your color proof will have that profile set as a target to simulate. Although offset has been regarded as the holy grail of printing because of the high quality it can achieve due to the high resolution output devices (Computer to Plate output devices “CTP” can achieve over 5000 Dpi in some cases) this Standardization process is not useful when dealing with other technologies like: Digital, LFP, Proofing, Fine art Reproduction, photo labs and Dye Sublimation and even Flexography or gravure printing. These processes need a fingerprint of the device or Characterization to get accurate color reproduction. This is because there is no set standard for ink, paper or Tone reproduction curve for these processes. In the end the goal is to have precise Colorimetric Lab Values from Capture all the way to reproduction taking into account the limitation of the output device’s gamut. In a nutshell your original, your digital file and your print should all have a very similar Lab value at the chosen Illuminant and observer angle (example D50 2°).
Experts say that an RGB file and the same CMYK file will not output the same result.
This is a myth that is false if your workflow is correctly configured. You can achieve the exactly same result with a CMYK file and an RGB file if the CMYK conversion is properly done. You can even have a Lab workflow that matches your RGB and CMYK workflow. We will teach you how this is done.
What is the difference between Standardizing to G7 or ISO Norm 12647-2.
G7 means Gray and your 7 primaries CMYKRGB. It uses the same colorimetric values as ISO Norm 12647-2 for substrates, CMYK inks and RGB overprints but it uses a different Tone Response curve than ISO Norm 12647-2. G7’s TRC target is 16% dot gain at 50% tint for CMY and 19% dot gain at 50% tint for K, whereas ISO Norm 12647-2 uses a TRC is 14.3% dot gain at 50% tint for CMY and 17% dot gain at 50% tint for K, rendering a cleaner output than G7. The calibration process is similar until the point of adjusting dot gain on press after that G7 makes an adjustment to gray balance reproduction so in the end you probably won’t have that 16% dot gain at 50% tint for CMY inks. In my experience both systems work well but G7 takes more work to achieve and it is harder to control over time. G7 is mostly used in North America and ISO Norm 12647-2 in European influenced territories.
Can I use G7 to calibrate my digital workflow?
This would not be recommended since your digital workflow needs to be calibrated and characterized and G7 is only a calibration with no characterization. Therefore, you would not be able to achieve the maximum gamut of your output device using G7 or ISO Norm 12647-2 calibration. On other hand you could simulate G7 or ISO Norm 12647-2 after you characterize your output device if that is your wish. You can also reproduce any pantone that falls within the gamut of your output device.
What differs in my Profiling method from the rest?
The main difference in my method of creating ICC profiles is the Ink restrictions. Most RIP’s Manuals encourage users to restrict their Primaries Visually looking for artifacts and Puddling. Some Rips do Chroma based linearization. I use a Chroma approach to ink restriction but Chroma is not the only thing we look for. This way we can make a printer have the exact same output at 720dpi than at 1440dpi. Also this way we can make all printers with similar gamut’s reproduce the exact same color. Also TAC and Black generation are very important factors.
Can my Neutral grays in a digital ICC Profiled workflow be as accurate as in G7?
The answer to this question is absolutely yes. The key is how good are you at creating your ICC profiles. If your profiles are done correctly your gray balance will be perfect from Highlights to shadows.. 0 in a and 0 in b from L white point to L Black point. Remember that color is described in Lab and the grey axis is at a 0 and b 0 from L 100 to L 0 you can also achieve perfect grey balance using the G7 calibration method but it will not eliminate characterization since ink and paper is not standardized and who tells you any different is not being totally honest with you. I can tell you that probably Neutral greys are simpler to achieve in a digital workflow. Offset has to many variables that digital printing does not have.