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  • Nth_man
    replied
    Originally posted by RomuloP View Post
    [...] for painting [...]
    Recently:



    Actually, we can see how it may be done:


    There's more in:
    https://krita.org/en/item/interview-with-ali-bahabadi/

    Leave a comment:


  • RomuloP
    replied
    Originally posted by oiaohm View Post
    Except this is half true. Yes when you map a individual color this works. When you map 2 or more this can cease to work. Mathematically says this is a problem.
    ...
    .
    No it is not, mathematically this is perfectly fine. I recommend you give a look at Nine Degrees Below Photography programmers guide to XYZ, RGB, ICC, xyY, and TRCs as a starting point, specially chapter Colors that weren't measured and Why so many RGB working spaces? Again, mostly, your complains and suppositions really don't matter, if you want yo assume what I was doing was spot color, you are wrong, we made a proof with a chemical proof generic profile and their instructions on the amount of black and cyan and result got perfect.

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  • oiaohm
    replied
    Originally posted by RomuloP View Post
    This could not be more wrong in fact, color spaces are infinite coordinate spaces, with coordinate transformations you can map any point from any color space to any other using XYZ color space
    Except this is half true. Yes when you map a individual color this works. When you map 2 or more this can cease to work. Mathematically says this is a problem.
    Safe color mapping for each spot color you need channel. So CMYK printer only has 4 channels so can only take 4 spot colors include K channel.

    What is the problem here you have failed to take in the difference between additive colours and subtractive ones. CIE 1931 XYZ color space is what you would be referring to by XYZ color space. XYZ color space is additive. CMYK is subtractive. This is one of the traps there is no black in the XYZ color space.

    Another fun point photoRGB has points outside the XYZ color space and that is need.

    The XYZ color space is in fact wrong. Humans with the condition commonly called tetrachromacy can see color that are outsize the XYZ color space by a large margin. Depending on the lighting as well printable colors outside the XYZ color space can also be visible normal humans without tetrachromacy.

    The color range of the XYZ color space was decided by a total of 10 people unfortunately those 10 people did not have best vision heck not even average for color detection for a human. What partly screwed them is their sex all the people who deterred the XYZ color space were male. Unfortunately odd part of humans is that tetrachromacy and other advance human vision traits only appear in people with two X chromosomes so females or Klinefelter syndrome males(these are insanely rare). Yes those who made the XYZ color space had average color detection for a male human but over half the humans are not male and its the female humans with the better vision. Yes the man problem where lady asks him to pick between 2 colors and not be able to tell the difference can 100 percent be the vision difference between male and female humans. So yes XYZ color space is another historic screw up. Yes people who don't know this subject always say what you said that you can use XYZ color space to map from one color space to another that would be possible of XYZ color space was correct in the first place.

    Originally posted by RomuloP View Post
    What is true is that many printers today will be able to do a better job converting from a specific RGB profile than a CMYK one simply because some printers are adding spot color or even blue, red or anything else, and if you can avoid CMYK completely, this turn to be great so nobody cares to work on mapping the printer profile to a proper CMYK profile for color proffing..
    One of the problems here your complete CMYK maths are wrong. CMYK software maths are not design to take account for the additive parts of the pigment(the inkj) instead only design to take account for the subtractive. This is why almost every time someone says they have their correct color profile for their printer for CMYK when you in fact test it they are in fact off.

    The problem here is not being able to use a spot ink profile per channel. This measures two different things the colours absorbed by a ink and the colours reflected by the ink that give two different RGB values being additive and subtactive. CMYK even with the color proffing is a hack its not designed for printing. The CMYK designed for print is CMYK spot printing that use per channel profiles and this is a different beast.

    The reality here is software CMYK and XYZ color space are screw ups and are done incorrectly. We really do need spot channel printing for printers where you can put the ink properties on each channel and have what ever number of channels the printer has. Most inks are both additive and subtractive. Less common ones are only additive or only subtractive they are not what is in your general printers. CMYK in software is based around a theoretical ink set of pure subtractive that does not exist in the common market space that people are incorrectly attempt to fix for by apply printer profiles designed on the theory of subtractive of course this is not working right.

    The levels of screw up here are insane. Yes people have got really stuck in their way with CMYK for printing are are not willing to step back see it wrong and see that they need spot printing methods so they can in fact configure the channels correctly for the inks. Yes a lot of print shops issues with having to do many samples with customers comes in a lot of time due to the use of CMYK and the problem how the calibration is off.

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  • mppix
    replied
    You two are cute!

    Leave a comment:


  • RomuloP
    replied
    Originally posted by oiaohm View Post
    This is just wrong. CMYK colour space does not cover what can be printed..
    This could not be more wrong in fact, color spaces are infinite coordinate spaces, with coordinate transformations you can map any point from any color space to any other using XYZ color space, maybe you are referring to some specific CMYK profile plus specific printer, but this is a printer limitation and mathematically saying, this is wrong. What is true is that many printers today will be able to do a better job converting from a specific RGB profile than a CMYK one simply because some printers are adding spot color or even blue, red or anything else, and if you can avoid CMYK completely, this turn to be great so nobody cares to work on mapping the printer profile to a proper CMYK profile for color proffing.

    The rest is just you making wrong assumptions about others work delimitations and demands and what is correct, wrong, good or bad around those assumptions.

    Originally posted by oiaohm View Post
    This what you said is kind of right. But when you are doing a custom painting or print you may have a color that is not based on cyan, magenta, yellow or black. Can you work out how this is now restricting yourself...
    Industrial printing on transparent medias like plastic with translucent art that ask for limitation on the amount of those specific components I just receive the limitations and use CMYK to do those limitations. What machinery they use? I don't know and don't care, simply prefer the smallest atrit path plus this is not my concern.

    And again, the rest is you making all sort of assumptions around "normal pressure and temperature conditions" that are plainly useless.
    Last edited by RomuloP; 03 September 2021, 12:35 PM.

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  • oiaohm
    replied
    Originally posted by RomuloP View Post
    Sure, but I still disagree, CMYK only purpose is printing and it is not specially needed in drawing, it is needed in printing when RGB or anything else is not adequate. Those tangent subjects you bring, like if CMYK is sweet or salty, they really don't matter to me, color spaces are only mathematical constructions to get job done, if I just want to comply with absolute rules like having 0% or 25% black or very strict percentual peer cyan, magenta, yellow and black, CMYK I will use.
    This is just wrong. CMYK colour space does not cover what can be printed. The first time the full sRGB colour space was printed in book was in the 1980s it used 32 different inks. Lot of paint you by the color is recorded in RGB of some form because the colour you can want to paint you walls of your house could be outside the CMYK colour space.

    The reality here CMYK is in fact not adequate for printing. This more clear when you go around a grocery shop looking at products on shelves finding more and more using colors out side of the CMYK color space.

    CMYK in printing originally is cost cutting. Spot printing has existed longer than CMYK and it is spot printing that is used to print product labels in most cases. This is somewhere between 4 to 32 colors. One will most likely be black(K) but does not have to be. Spot printing has been able to do the full RGB color space on paper for decades now. In fact spot printing can stuff that RGB cannot represent.

    The reality here you don't need CMYK to print. CMYK can be implemented inside spot print system. Yes spot system have 4 inks of CMYK in the machine and its printing CMYK. Just like you can load a CMYK printer with RGBW ink and have it print full RGB.

    The CMYK implemented by photoshop originally that come the software standard CMYK does not match the behavour of ink and never has. This is the problem if CMYK only purpose is printing then it should make a ink standard.

    RomuloP the big thing here print shops have custom loaded printers with inks for ages. Yes depend on the printing firm will depend if they want CMYK or RGB or some other horrible spot system. There are more cases that places in fact want RGB files and people send them CMYK that just annoy them. You think about it you have a 12 ink printer that may not be a CMYK base printer that might be a 80% sRGB printer.

    Photoshop CMYK was not designed for printing orgianlly it was designed for software color mixing close to ink mixing.
    Originally posted by RomuloP View Post
    if I just want to comply with absolute rules like having 0% or 25% black or very strict percentual peer cyan, magenta, yellow and black, CMYK I will use.
    This what you said is kind of right. But when you are doing a custom painting or print you may have a color that is not based on cyan, magenta, yellow or black. Can you work out how this is now restricting yourself.

    Spot colour system replicates the old painters palette board a lot. Also it pays to look at that old painters palette board . That old board painters palette board generally has 6 colours red of some form a yellow of some form a blue of some form and green of some form then black and white. Yes cyan is a merge of the green and the blue inks that end up narrowing the colours that can be represented in a print massively. Yes a lot of spot colour printing is 4 colour with black and white yes decanted blue and green.

    CMYK really has been crippling our printers. CMYK in the printing world was done for cost cutting. The software define of CMYK does not match the print define of CMYK leading to a lot of mess in the middle.

    Most people don't know that BGWYK printers exist. Black being called K is that because Blue had already taken the B.

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  • RomuloP
    replied
    Sure, but I still disagree, CMYK only purpose is printing and it is not specially needed in drawing, it is needed in printing when RGB or anything else is not adequate. Those tangent subjects you bring, like if CMYK is sweet or salty, they really don't matter to me, color spaces are only mathematical constructions to get job done, if I just want to comply with absolute rules like having 0% or 25% black or very strict percentual peer cyan, magenta, yellow and black, CMYK I will use.

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  • oiaohm
    replied
    Originally posted by RomuloP View Post
    There is nothing funny wrong, It is that we just disagree, more and more as comments go. For example, most people don't think the main reason for CMYK is drawing, because it is not, CMYK purpose is printing, be it in photo edition, drawing and painting, scenographic printing, etc... All them use CMYK differentlyto achieve the same purpose, printing according to demand on printers with specific demands. CMYK has no special use for drawing itself or painting emulation or whatever.
    Adobe RGB from 1998 was in fact made to have enough colour space to cover the printers at the time. CMYK colour space does not cover 1998 printers let alone the current ones.

    Here is what is super fun with CMYK
    Lets take the Cyan, Magenta, Yellow, and Key ink from a real 4 ink printer and we colour test it and we compare the results what the CMYK colour space says these should be. Guess what they are not even close.

    Get more interesting why does paltone have as core standard RGB values. Interest enough this is because how you check if a colour is right in print shop is using light based tools yes you spectrocolorimeter. Interest enough the first high end printer with integrated spectroradiometer is 1991. Yes surprise right to check the printing result you need RGB values not CMYK valves.

    Yes integrated spectroradiometer done right a printer can be monitoring its ink colour and be adjust its print based on the detect color at the time.

    The reality here is CMYK as a term is used in printing and in software. Problem is they don't in fact match. RGB is used a lot more in printing than think. Lot of you really high end printers want nothing todo with CMYK. I have had people want me to re do a picture because it did not print well for them and all I did to fix it was send RGB original instead of the CMYK conversion to the printer because the printer was auto colour correcting so wanted RGB not CMYK.

    Yes CMYK started out as print system. But the CMYK colour space in software is not that. The idea that CMYK is for printing in programs like photoshop is that people have jointed two independent things to each other because they have the same name.

    https://www.merckgroup.com/en/brands/pm/spectraval.html
    Also this stuff really does surprise people. Turns out with the right inks and black paper in a standard commercial ink printer you can in fact print the full pro photo RGB colour space. The ink chemistry is not new either its from the 1960 designed for anti counterfeiting marks on money. Yes this is a RGBW ink instead of CMYK ink.

    The RGBW does not work well on white paper and CMYK does not work well on black paper.

    Hard and fast rule that people have in the heads that printing has to be CMYK is wrong. You do need to check your printer or print shop that it is CMYK that printer want. RGB is a lot more commonly needed than many think or spot colours. Yes in some print systems/shops its possible to do a RGBWK inks this does work on white paper because the printer puts the K on first and drys that for the black background to the picture. Yes a RGBWK on white paper or a RGBW on black paper starts giving the same quality of photo as what you use to get by film processing.

    Surprise to most people that old school photos are reflective pigment so additive where you CMYK is a subtractive of course since RGBW are reflective/additive lot simpler to look like a old school photo you are working in the same pigment type.

    The realities of items like RGBW inks have really been delayed. The idea that spot colour printing does not have colour mixing as well has been another problem. Lot of the packaging on products on shelves is not CMYK printered but instead multi channels of spot colours mixed with each other. This multi channel of different spot colours existed before photoshop. CMYK is just the 4 channel one designed for white paper. Brown cardboard if you are printing on that CMYK does not work well.

    Hard problem here adobe has in some ways abused the control of the PDF standard. Supporting the new inks like RGBWK setups is going to require tool changes to in fact support configurable colour channels. Yes RGBW is only covering the RGB colour space this is not covering like the colour change inks based on angle and so on.

    Sad part here we have had the colour space idea wrong. All the colours that can be shown on a monitor can be printed. Many colours that can be printed cannot be shown on a monitor due to colour change effects based on angle or reflective nature. We have had basically 3 decades of incorrect education about printing. Yes over that 3 decades adobe has basically doubled down on the incorrect path many times over and people have followed like sheep.

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  • RomuloP
    replied
    Originally posted by oiaohm View Post
    ... This is what is so funny wrong ...
    There is nothing funny wrong, It is that we just disagree, more and more as comments go. For example, most people don't think the main reason for CMYK is drawing, because it is not, CMYK purpose is printing, be it in photo edition, drawing and painting, scenographic printing, etc... All them use CMYK differentlyto achieve the same purpose, printing according to demand on printers with specific demands. CMYK has no special use for drawing itself or painting emulation or whatever.

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  • oiaohm
    replied
    Originally posted by RomuloP View Post
    almost everything in the media industry is a VFX tool, this is why I see no sense in discussing Photoshop out of its primary purpose as photography manipulation, because it is there that it feets well, as is in concept art that Krita fits well for VFX.
    This is what is so funny wrong . Photoshop stated primary purpose is not photography, Photoshop stated primary purpose is drawing. Yes if you look at Photoshop 1.0 it looks like MS paint with basically the same functionality.
    https://www.youtube.com/embed/Tda7jCwvSzg
    Yes this is the first Photoshop demo reel where people get the idea that the primary purpose was photography manipulation but this is not 1.0 but a latter revision. The original 1.0 photoshop does not have calculate bit or all the color depths these were added on in the revisions so the original 1.0 photoshop does not fall into signal processing.

    Photoshop is in fact a drawing tool that over time photography manipulation features and other things were tacked on.

    Functionality wise Krita exceed Photoshop 1.0.7 as in the first demo that pushed Photoshop as a photography manipulation tool.

    Krita does have enough functionality to start being used as a photography manipulation tool. Thing to remember there are drawing programs that do not fall into signal processing/Digital image processing.

    The original logo of Photoshop the eye is hand drawn. Yes Photoshop basically started with the same goals a krita of being able to draw really well then see the tools being made for this could used with photos and photos is a bigger market. Yes this is what leads to the cmyk stupid error in those working with photos. CMYK was in photoshop from the start because it was a drawing tool and was attempt to replicate painting on paper.

    Fun right the biggest common mistake a new person has done to photographic work of converting to CMYK instead of staying in RGB processing comes straight from photoshop first stated primary purpose being drawing so resulting in CMYK functionality being included for that use case. Yes this is add a little human stupidity that if the feature is include in a tool pushed for photography manipulation that CMYK has to be used that turns into years and years of totally wrong photo processing.

    All the Digital image processing software do evolve over time. Krita and photoshop really have the same primary purpose just photoshop has years of evolution that have left original primary purpose very neglected.

    This is a problem as a tool like gimp/photoshop increases their features out it comes more and more simple for different areas of tools not to get the attention they should. Of course this leads to people like you miss stating what the primary purpose was. Of course means it comes really simple to miss that there is functionality in photoshop that does not make sense for some thing with the incorrect stated primary purpose but things does make sense when you use the original primary purpose.

    Having less features is not a bad thing if all those features are being properly developed. Having too many features is how you end up with a gimp/photoshop where they don't match their original primary purpose very well any more.

    Gimp ignoring CMYK processing for a very long time was because for photo work and prep work for websites and the like CMYK make no sense at all. The existence of CYMK in the first version is kind of marker that you are starting with a drawing tool not a photography.

    https://en.wikipedia.org/wiki/Quantel_Paintbox

    The history of photography manipulation starts with Paintbox that is really a 2d VFX system. Yes they attempted to sue adobe over photoshop for including VFX functionality in their drawing program in the photoshop 1.0 time frame. Yes Paintbox primary was work with video not still images yet people would also use it for still image work. Yes Paintbox here does not have CMYK support at all.

    The lines between VFX and Photograph manipulation gets very blurry and is crossed over many times over the history of people doing photograph manipulation and VFX work.

    The reality is what photoshop looks like today is what krita could end up looking like if for 2-3 decades people go after the largest market instead of keeping the core functional good. Yes being aware of the correct original stated primary purpose of photoshop allows you to see the warning for krita future if particular development route it taken.

    There is something interesting as well. VFX targeted solutions(that is their primary is VFX) how many have CMYK in their first form then answer is zero and most never support CMYK at all. Visual effects is in fact talking about messing with light effects. Light effects make more sense in RGB or YUV not CMYK. Photograph manipulation the most common thin you are messing with again is light so CMYK makes limited sense.

    Yes photoshop and krita mix of supported colour systems tells you something. The mix is what you would expect to see in a drawing program that at time is going to attempt to emulate painting and the like. Like it or not particular features exist in programs for particular use cases. Most people don't think the main reason for CMYK is drawing.

    There are a lot of color printers that only take RGB in and do internal conversion from RGB to ink even in major print shops. Why is this simple you may have different batches of ink with different colour so need to do different transformation this was even the case before photoshop was released. Fun right how to add a extra transformation by submitting to a print shop you work in CMYK resulting in them having to covert it back to RGB before the printer coverts it back into inks. Yes each extra step introduces risk of a maths error.

    One of the gimp lead developers presentations on the research they did for planing how gimp would move out of RGB only to more color type support got really interesting. They did in fact send people to over 2000 different print shops to see workflow and spoke to the companies that make their gear and got the history. The big thing that found was the CMYK stuff was not as important as a lot of people thought it was for printing in fact it causes a lot of production problems adding in extra transformations. This lead to the question if CMYK was not for printing what the hell was it really for? That leads back the answer that its for drawing software to emulate working with real work inks kind of yes it based on the idea of real print shops using CMYK of printing that most high grade production printers have not used for over 30 years now. In your advanced home printers you see 6 channel printing and greater this should have been a warning CMYK is not going to be right. Horrible point here lot of 6 channel printers can print colors you can not represent in the CMYK color space or the sRGB color space. Yes this put the GIMP developers in a very strange location the feature people are demanding over and over in bug reports turns out to be the wrong feature for high grade printing yet they were asking for it for high grade printing(yes this is CMYK). CMYK is a historic hang over it was something that was used but printer have moved on to 6 colours and targeted spot colors(that a fun one).

    Target spot colors is when instead of having CMYK ink or equal you now have 32 bit integer value application of some standard colour like a pantone colour this could be up to 64 channels. Yes these go why outside CMYK colour space and goes into areas RGB color spaces cannot cover like metallic inks.

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