I am wondering whether exist a way how to transform colors of specific CMYK color space (lets say FOGRA39) to CIEXYZ.
I know how to sRGB to CIEXYZ, as there are dozens of 'how-to' on internet.
But I never found similar transformation equation for FOGRA39 (or any other printing color space).
Have somebody experiences to share them with me?
Thank you.
Short answer
These colorspace transformations are not described as formulae but as (mostly) look-up tables in ICC profiles (.icc files).
Longer answer
The color values in some color spaces are related to other color spaces via relatively simple closed-form expressions. Well known examples are the relation between XYZ and Lab, and the relation between sRGB and XYZ that you mentioned. Often the corresponding transformation formulae are obtained from color-theoretical considerations.
On the other hand, the color spaces corresponding to actual or idealised printing processes (such as FOGRA39) are characterised by performing actual printing experiments. This is done by printing a large number of different color patches under controlled circumstances on the device that is being profiled (a printing press for example), and measuring the color of the resulting printed patches with a photo spectrometer.
These measurements do not yield a simple formula for conversion between color spaces, but instead a table of a large number of pairs of color values: the known amount of ink printed (e.g. CMYK) versus measured color. This color profile table is then typically stored in a standardised (file) format: the ICC profile. Here is an ICC profile for FOGRA39. (Actually, while look-up tables are an important part of typical ICC profiles, ICC profiles also support parametric curves and matrix transformations to do colorspace conversions.)
For most users, the ICC file format is too complicated to parse and interpret, and color management too cumbersome to implement oneself from scratch. If you need to perform color conversion to or from a color space represented by an ICC profile, one typically uses the color management facilities offered by the operating system, or a by third-party library.
Virtually all color management systems (CMS) in use today have support for ICC profiles, and their APIs have support for color conversion using ICC profiles.
The major platforms Mac and Windows have their own color management systems and APIs that you can use, and on Linux open source solutions (such as little cms) are available as well. The specifics however depend on the platform one targets, and programming language one intends to use.
Related
I've noticed that the GPU I'm running on Vulkan doesn't support so many of the R8G8B8_UINT formats but does with the R8G8B8A8 FORMATS. Also the same thing with many others like R32G32B32_SFLOAT. I've noticed that's also the with other GPUs I've seen on OpenGPU database.
Is this normal? Why is this so? Is it normal with other graphics APIs? Is it to align values/texels to a "round/nicer/aligned" number of bytes? How are you supposed to get around this? I'm having trouble seeing how throughout your code you'll be interacting with images that you have no idea what colour format they are, which complicates things both on host code and in shaders.
Also if I have 3 channel colour format image on the host and I want to use with Vulkan and say R8G8B8 or R32G32B32, do I need to loop through the image manually and rearrange the texels?
24bpp formats are hard to optimize in graphics hardware. This is why there is no "R8G8B8" format even defined for the DirectX Graphics Infrastructure pixel formats used for Direct3D 10, 11.x, and 12. Almost all the work is around optimizing 32bpp formats which is why RGBA32, BGRA32, etc. are much more commonly supported. 64bpp and 128bpp formats are multiples of 32-bits, so it makes just the 24bpp format the 'odd-man out' in many cases. You often can find a B8G8R8X8 (32-bit) format which is about as close as you get to 24bpp.
Some hardware will find ways to support 24bpp formats (which were supported by older Direct3D releases for example), but it's generally less efficiently rendered.
Similar issues arise with 96bpp formats (R32G32B32 floating-point). For Direct3D Hardware Feature Levels, this format is always optional and when implemented it's typically done as three 32-bit floating-point planes, one for each color channel.
Im trying to calibrate/adjust my screen color configuration more towards a specific paint color like RAL.
Im using Encycolorpedia works great tot determine (what color) and even deltas between specific paints. However my screen doesn't come close to the real life situation, I've received a color wheel and oh my gosh... what a huge difference. So ordering paint online is an absolute no-no.
The big question how to close that gap between Adobe RGB Color and paint-colors like (Sikkens) RAL or Pantone? Something within the ICC profile of the monitor (which is a Samsung)?
I know there are color-spiders to calibrate screens, but I really wonder if there's an online database or which corrections or calibrated settings for monitors ?
You cannot do it. And possibly you do not have correct understanding of ICC, colour profiles, and RAL.
If you want to calibrate your screen, you should have a good screen (I recommend one "hardware calibrated", so you will not lose colours), and a calibration device. So you will have a good calibrated monitor, which display the correct colours. You will use the ICC file to tell the screen (or graphic card) how to handle colours, and to the program, so they know which range of colours they can use.
A ICC profile just tell a screen how to convert numbers (colours). An AdobeRGB profile will not make your screen to see AdobeRGB colours, it will just transform the colours so that you will have the "numbers" as expected by a 100% precise AdobeRGB screen (which never exist, so it is better to use device specific profiles). If your screen is not 100% AdobeRGB it will display some colours in an unexpected way. Our eyes may adapt colours (so for a single person, this is not a huge problem, but if you are doing a magazine, with 15 graphic editors, the reader want consistency (there is not time to adapt eyes for every image).
But then you go to Pantone and RAL: there are different kind of colour description (really, forget RGB for such colours: you need spectral distribution). These are for real objects, so they are seen with different lighting conditions (illumination), and an object can be seen in different colours (as RGB), but being of the same colour (as paint/dye).
And Pantone and RAL have discrete colours (enumerated colours, not homogeneously distributed). And for screens we just use LUT or LUT3D, so simple matrix conversion of received colour numbers to displayed colour numbers). Not a thing a screen can do so quickly (60 time per second, for every pixel).
Finally: screens are very different technologies as objects. There are some screens which create the same feeling (and also they seems more "opaque"), but this is not a thing we can every reach with standard (or most of good wide-gamut screens). And screens sucks on yellows and yellow greens (now I'm thinking at various RAL used for emergency). Out of reach for most monitors. An interaction with a soft printing is necessary (and you need a [frequently] calibrated printer).
Note: usually you get drivers for your monitor (look online for your monitor manuals and drivers [and look just at manufacturer website]). They will usually have the "driver", which it is a ICC profile. But this is just a "standard" profile. Monitors will change with time (either cold [at start-up] to hot), but also with long period using it. And different batched may be different (especially if produced in different places, common for very common monitors). If you use their profile, you should get better colours. If you calibrate yourself, you will have much better colours, but as I wrote, it is probably not possible to have good/very good matching colours.
Given two seperate computers, how could one ensure that colours are being projected roughly the same on each screen?
IE, one screen might have 50% brightness more than another, so colours appear duller on one screen. One artist on one computer might be seeing the pictures differently to another, it's important they are seeing the same levels.
Is there some sort of callibration technique via software you can do? Any techniques? Or is a hardware solution the only way?
If you are talking about lab-critical calibration (that is, the colours on one monitor need to exactly match the colours on another, and both need to match an external reference as closely as possible) then a hardware colorimeter (with its own appropriate software and test targets) is the only solution. Software solutions can only get you so far.
The technique you described is a common software-only solution, but it's only for setting the gamma curves on a single device. There is no control over the absolute brightness and contrast; you are merely ensuring that solid colours match their dithered equivalents. That's usually done after setting the brightness and contrast so that black is as black as it can be and white is as white as it can be, but you can still distinguish not-quite-black from black and not-quite-white from white. Each monitor, then, will be optimized for its own maximum colour gamut, but it will not necessarily match any other monitor in the shop (even monitors that are the same make and model will show some variation due to manufacturing tolerances and age/use). A hardware colorimeter will (usually) generate a custom colour profile for the device under test as it is at the time of testing, and there is generally and end-to-end solution built into the product (so your scanner, printer, and monitor are all as closely matched as they can be).
You will never get to an absolute end-to-end match in a complete system, but hardware will get you as close as you can get. Software alone can only get you to a local maximum for the device it's calibrating, independent of any other device.
What you need to investigate are color profiles.
Wikipedia has some good articles on this:
https://en.wikipedia.org/wiki/Color_management
https://en.wikipedia.org/wiki/ICC_profile
The basic thing you need is the color profile of the display on which the color was seen. Then, with the color profile of display #2, you can take the original color and convert it into a color that will look as close as possible (depends on what colors the display device can actually represent).
Color profiles are platform independent and many modern frameworks support them directly.
You may be interested in reading about how Apple has dealt with this issue:
Color Programming Topics
https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/DrawColor/DrawColor.html
You'd have to allow or ask the individual users to calibrate their monitors. But there's enough variation across monitors - particularly between models and brands - that trying to implement a "silver bullet" solution is basically impossible.
As #Matt Ball observes calibrating your monitors is what you are trying to do. Here's one way to do it without specialised hardware or software. For 'roughly the same' visual calibration against a reference image is likely to be adequate.
Getting multiple monitors of varying quality/brand/capabilities to render a given image the same way is simply not possible.
IF you have complete control over the monitor, video card, calibration hardware/software, and lighting used then you have a shot. But that's only if you are in complete control of the desktop and the environment.
Assuming you are just accounting for LCDs, they are built different types of panels with a host of different capabilities. Brightness is just one factor (albeit a big one). Another is simply the number of colors they are capable of rendering.
Beyond that, there is the environment that the monitor is in. Even assuming the same brand monitor and calibration points, a person will perceive a different color if an overhead fluorescent is used versus an incandescent placed next to the monitor itself. At one place I was at we had to shut off all the overheads and provide exact lamp placement for the graphic artists. Picky picky. ;)
I assume that you have no control over the hardware used, each user has a different brand and model monitor.
You have also no control over operating system color profiles.
An extravagant solution would be to display a test picture or pattern, and ask your users to take a picture of it using their mobile or webcam.
Download the picture to the computer, and check whether its levels are valid or too out of range.
This will also ensure ambient light at the office is appropiate.
I have an SWF file with only vector illustrations in it (no bitmaps). Is there a way to improve colour consistency across different monitors?
Colour management is a very complex topic and the more I read about it the more confused I become. There's this thing called ICC profiles which are supposed to convert colours into device independent color spaces, but of what use is that?
ICC profiles provides a way to map the colors that your monitor thinks it's showing (the bitmap/image, or other graphics) to what it is actually outputting on the panel. Using software that supports these profiles you can get more consistent colors.
The basic flow is this:
A program reads the graphics file
The program uses the icc profile to compensate for your monitors inadequacies
When you change monitor, you change the icc-profile to match the new monitor
When you print, you use a different icc-profile suitable for the printer to compensate for the printers inadequacies
This is meant to make sure that the colors on screen match the printed paper and is generally not something that scales beyond artsy stuff.
If you want consistency among your own monitors you would "just" have to calibrate them and configure the profiles for your monitors. I don't know how to do this, but my guess is that Adobe has pretty good docs about it.
If you want something like consistent colors on say a flash game across different users, I don't think that is possible. In any case it would be the clients job to manage the ICC-profile and the flashplayers job to support the compensation.
In any case, the part about adjusting the monitor settings before doing the calibration is because this changes the color reproduction of the display, so if you change the settings you will have to re-calibrate the display.
The problem is you have no control over your user's monitor (type, make, age, adjustment).
ICC profiles are designed to interpret between a real-world device (like a camera, monitor or printer) and an independent working colour space (see here for an explanation).
Flash 10 "supports ICC-profiles" only in the sense that you can specify whether or not flash should adjust it's colours according to the local ICC profile (chosen by the user to suit their monitor). So the most you can do is set stage.colorCorrection = ColorCorrection.ON; (and it won't work for Unix or Linux).
Otherwise, you could consider making the colours shown in your SWF file to be user-configurable: they can then adjust things to their own liking - perhaps via some form of colour-calibration.
Since the vast majority of monitors are 16-bit color or more, including mobile devices, does it make sense to even consider web-safe colors when choosing color schemes? Or is it something that ought to be relegated to history as a piece of trivia?
For those of you that don't know what web-safe colors are:
Another set of 216 color values is commonly considered to be the "web-safe" color palette, developed at a time when many computer
displays were only capable of
displaying 256 colors. A set of colors
was needed that could be shown without
dithering on 256-color displays; the
number 216 was chosen partly because
computer operating systems customarily
reserved sixteen to twenty colors for
their own use; it was also selected
because it allows exactly six shades
each of red, green, and blue (6 × 6 ×
6 = 216).
The list of colors is often presented
as if it has special properties that
render them immune to dithering. In
fact, on 256-color displays
applications can set a palette of any
selection of colors that they choose,
dithering the rest. These colors were
chosen specifically because they
matched the palettes selected by the
then leading browser applications. [Wikipedia]
For me web safe color palette is no longer primary concern. Optimize for the largest target audience.
According to w3schools site visitors:
In January 2009 1% of site visitors had 256 color displays, 95% of users had
24 or 32 bit.
[Update] In January 2015 0.5% had 256 colours, 0.5% had 24 bit and 99% had 32 bit
I found similar numbers from a business app site that I look after:
32-bit 79.01%
24-bit 15.64%
16-bit 5.27%
8-bit 0.08%
I don't think web safe colors are relevant any more. To me, a much bigger problem for smartphones are all the fixed-width 960-pixel wide web pages.
I think the most important thing when choosing a colour palette is keeping in mind colour-blindness. There are a few different types that I know of, but the main thing is making sure that you have enough contrast between colours.
For example green text on a red background might be easier for some to read, but very difficult or maybe impossible for others (5-10% of males!), especially if the values of the colours are close.
For those of us (like me) that didn't know exactly what web safe colors are, they were
developed at a time when many computer
displays were only capable of
displaying 256 colors. A set of colors
was needed that could be shown without
dithering on 256-color displays; the
number 216 was chosen partly because
computer operating systems customarily
reserved sixteen to twenty colors for
their own use; it was also selected
because it allows exactly six shades
each of red, green, and blue (6 × 6 ×
6 = 216).
The list of colors is often presented
as if it has special properties that
render them immune to dithering. In
fact, on 256-color displays
applications can set a palette of any
selection of colors that they choose,
dithering the rest. These colors were
chosen specifically because they
matched the palettes selected by the
then leading browser applications.
It's hard to imagine any of this applying to today's modern displays, since almost nobody runs their display in 256 colors anymore (unless perhaps they are playing an old version of Leisure Suit Larry).
It depends what you mean by web safe colours.
In terms of 16bit colour it's probably not worth worrying about. However Colours do not appear the same across devices. This can lead to all sorts of problems particularly if a designers gamma settings are different to your particular monitor set up.
So you still need to test your design across multiple set ups.
In my opinion, it's just history.
Yes, it's definitely a thing of the past. Place its importance right next to your marquee tags.
IMHO the point is really moot. Colors that aren't web safe are dithered anyway. It may not look the best in 256-color modes but as long as functional elements of the page/applications are not dependent on those colors it will not disturb the user experience that much.
Also most users surfing in 256-color modes will be aware of the fact colors will be dithered as I don't think that a lot of sites adhere to the web-safe colorschemes anymore.
According to research, even the web safe colors were not web safe. It was an interesting idea while it was relevant, thankfully that's over now.
Web safe colors are pretty much not a problem anymore unless you are dealing with consumers that will have legacy (think > 10 year old) video display equipment.
It's still important if your target very poor to developing nations, such as countries in here south asia. I personally have a full blown IPS monitor with Windows 10, so it's not a problem to me, but we are minorities, and majority of them have old hardware/computers/operating systems except mobiles phones, as it's cheap to buy a latest mobile phone, but computer hardware are expensive due to the taxes/ import cost etc.. compared to the salary of an average person.I personally witnessed many people still use old Windows XP, 98 PC with 256 colors on Pentium 4 processors. So if you target such audience, it's better to use web safe colors, but if you are doing a business it's not worth, as they are less likely to be your customers, but if you are doing an information site, a blog, an activist site that people can read and get informed without having to pay for something then always use fallback theme or something with web safe colors. since such people are mostly on windows xp/98, try to detect the OS, and if the user is from such operating systems, then use the fallback theme.
So remember that, most of people in this world are poor, and most of people still use old hardware and technologies. If you want to cover them all without working a lot hard on your current theme, then always use fallback themes. One for old mobiles, one for old desktop displays, one for modern displays and modern mobiles (responsive)
Some colors do not display on some mobile devices. (trying to make a list)
The title bars are supposed to be a blue fade from CSS:
background: linear-gradient(to bottom, #0099CC1, #0033CC) repeat-x scroll 0 0 #006DCC;
On many devices the background is not visible, and the header looks like white-on-white.
So, I'm just trying to explain the tip to determine browser-safe colors just by looking at its hex code
For a hex color #xxyyzz, the color is browser safe if
For pairs:
position 12 i.e xx values are same
position 34 i.e yy values are same
position 56 i.e zz values are same
Allowed values are
0
3
6
9
C
F