A few color management questions

Discussion in 'Beyond the Basics' started by kkamin, Sep 22, 2009.

  1. kkamin

    kkamin TPF Noob!

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    1. I have a macbook and have decided to use sRGB for while until I learn more about
    color management. Can macbook display the full gamut of sRGB on screen? (If
    not, can Photoshop tell you if something falls out of the monitors display
    capability?)

    2. I want to calibrate my laptop screen the best I can. What I understand is that I
    am not calibrating it to a color profile, but am just calibrating so it is
    accurate piece of hardware, right?

    3. How good is the calibration utility that comes with OSX? I'm going to get the
    X-Rite i1 Display, is it worth it?

    Is there anything else I need to know to get started. I want to keep things simple, use sRGB for now, have the things on my laptop look close to what my pro printer will give me.
     
  2. Snyder

    Snyder TPF Noob!

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    Well first off why did you decide to shoot on sRGB? By doing so you are limiting yourself to a smaller color palette. Adobe RGB is better. Yes most typical monitors can handle color display the problem with out of gamut issue is when it comes to printing. I use a huey pro to color calibrate my monitor its not the best out there but it gets the job done. But this is just some very general info.
     
  3. musicaleCA

    musicaleCA TPF Noob!

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    Nooo, Adobe RGB will only add to confusion, since managing such JPEGs in post correctly requires some level of knowledge of colour management, to say nothing of colour space conversion, which is a nasty kettle of fish.

    No it can't. MacBook's and MacBook Pro's have a relatively low gamut, and can't display the full gamut of RGB. They're only around 6-bit, while the sRGB colour space is 8-bit. A marginal difference, but it will mean that you have to pay attention to the RGB values for pixels you're inspecting; a pixel or group of them may appear to be over-saturated (exited-out), when in fact it isn't.

    The calibration utility with OS X is reasonably okay, as long as you are meticulous and careful throughout the process. A hardware calibration system will always yield better results, but I haven't noticed any appreciable difference in colour matching.
     
  4. kkamin

    kkamin TPF Noob!

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    Thanks!

    -What kind of monitor can I get that will show the full gamut of sRGB? I've done some quick online browsing and it doesn't seem to be a standard tech spec.

    -Do you think I can still use my Macbook for color correction?
     
  5. musicaleCA

    musicaleCA TPF Noob!

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    Most PVA monitors (well, all, TMK) should display the full sRGB gamut. Apple's cinema displays are S-PVA and fit the bill, though are expensive, if you want to stick to Apple hardware for some reason.

    Yes, you can stick to the MacBook for colour correction, if you mean adjusting white balance and stuff like that. I've only been using a MBP for editing, and my photos look fine. >.>
     
  6. Garbz

    Garbz No longer a newbie, moving up!

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    Ok Hold your horses everyone.

    1. Stick with sRGB, that's a good decision. AdobeRGB has a larger gamut yes, but you know you need to be able to print that larger gamut and capture that larger gamut. For most of the visible work unless you use a polariser and bump up the saturation afterwards your image will fall within the sRGB gamut, and the only exception to that rule is orange sunsets which tend towards yellow when constrained to sRGB. AdobeRGB is *better* if and only if you have a killer scene with some ludicrous colours, and you print on something like an 8 colour printer, or go to a lab that'll charge you a fancy $20 per small print. If you don't do this you won't notice any benefit at all from AdobeRGB. In fact all you get is the disaster headaches from having to remember to do colour conversions and be aware which colour space your images are in before you upload them to the net or send them to your friends who may just see it as wrong. You bypass all these issues with sRGB, since it's the standard.

    TN panels can display the full sRGB gamut. The 6bit issue comes into branding. It can't display every colour within the gamut smoothly from black to the most saturated red green or blue, but it will most likely display the full gamut (i.e. the chromaticity of the red should be the same as any other screen for the sRGB value of (255,0,0))

    Photoshop can draw middle grey any colour value that falls outside the set colour gamut. This is called softproofing. Read this: http://homepage.mac.com/ilyons/pdf/ps6_sp.pdf

    2. You are calibrating a colour profile but not the one you are talking to. There's 3 types. Input profiles, Working profiles, and Output profiles.
    Input profiles are what is used to convert say Scanner data or Camera sensor data into Working profiles.

    Working profiles are the range of values the current file has. It defines that the value of RGB(128,64,64) will have a certain chromaticity. For instance sRGB(128,64,64) = AdobeRGB(114,66,66) = ProPhotoRGB(85,57,50). All of these have different values in the file, but all of them are the same colour to a colour aware program.

    Finally you have output profiles. This is what you are calibrating. A non-colour aware program will say ok you have a value that we assume is sRGB in the file, lets send it to the screen and assume the screen is sRGB. Photoshop will open the file, look at the working profile, load the colour profile for your display, and send to your display driver and adjusted version so that what is in your display profile accurately reflects what is in the file. The display profile is created by your calibration unit. The same applies to the printer which also has a different output profile, except this conversion is often enough handled by the printer driver.

    3. The calibration utility that comes with OSX I believe is one that uses your perception to adjust settings. I'm not sure on the details. If that is the case then it's crap. Don't worry though pretty much any calibrator you buy should have some software for OSX. The Huey as recommended above is a good choice. I own an iOne Display 2 and I will wholeheartedly recommend that one. Another choice is the Spyder 3. Shop around if you want, but essentially they all do the same thing.
     
  7. kkamin

    kkamin TPF Noob!

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    Thanks for your response. I'm a little confused still. I know my Macbook is only 6bit, but sRGB is 8bit. People are seeming to say that the Macbook is still good enough though for photographic color correction, but that confuses me if the full gamut of colors is not visible. What kinds of problems, if any, will I encounter since I cannot display the full gamut? I work inside Photoshop. My photography will be for both web output and print (the printers print light onto photo paper and process it chemically).

    Thanks for taking the time.
     
    Last edited: Sep 23, 2009
  8. Stosh

    Stosh TPF Noob!

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    I don't know anything about mac, but if I'm interpreting what Garbz is saying correctly, then he's saying the 2 missing bits won't have anything to do with the width of the full gamut, but in the intermediate shades of each color. In other words if you put an 8 bit monitor next to a 6 bit monitor and displayed black on both, they would look the same. If you displayed pure white or any other pure color, they would look the same. But if you displayed some random intermediate shade of a color on the 8 bit, it may be a value that the 6 bit would have to either round up or round down to display it, but it would be almost indistinguishable.

    And I think when you quoted him his word "branding" was supposed to be "banding". This is when you display a smooth progression from black to any color. The 8 bit would be smoother. The 6 bit would show some banding. The banding comes from having to round up or round down numerous values to display it on it's 6 bit capability.
     
  9. musicaleCA

    musicaleCA TPF Noob!

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    Yay! We squeezed another educational post out of Garbz. W00t! :lol:
     
  10. Garbz

    Garbz No longer a newbie, moving up!

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    Stosh explained it well what I meant with gamut. But my opinion on the rest of the post is No. You're going for one of the best processes for printing images, and are using the worst possible device to edit your image (a laptop). Laptop screens are simply not good for any serious editing work. Here's a quick example why: http://www.thephotoforum.com/forum/...-ips-display-vs-laptop-warning-lots-pics.html . There's no decent repeatability between edits on a laptop or any TN film LCD due to changes in viewing angle causing changes in the tonality and colour of the image. Apple laptops are a little better than many others but this still applies. That said editing on a macbook pro is still better than not editing at all.

    Also you won't ever display the full printing gamut of some of these chemical printers, but then often you won't have to. If you go outside and take some average snap there's a very good chance every colour recorded fits nicely inside sRGB. It's only when you start doing strange things like very colourful HDRs, shooting with polarisers and the saturation bumped up, shooting neon lights, or nuclear coloured sunsets, that the extra gamut makes a difference, and even then the difference is slight. Wide gamuts are something that you would notice side by side against another standard print but rarely if ever something that can be spotted in isolation. In any case you can still use wide gamuts when editing, just that the colours from the print won't look the same as what you see on the screen, not that they will anyway because you're editing on a laptop.
     
  11. Plato

    Plato TPF Noob!

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    Yet Adobe recommends ProPhoto RGB.
     
  12. Garbz

    Garbz No longer a newbie, moving up!

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    Of course they do. Adobe is a company which produce professional products to the highest quality. There's no debate that ProPhotoRGB has the largest gamut, and along with a 16bit process can bring out the very most colour information available. Adobe will recommend things that their software is capable of to show how much better they are than their competitors.

    What is under debate though is if the effort is worth it. Short answer NO! Long answer. No unless you fall into a very very very specific set of conditions where you have any gains from the process at all, those being:
    a) have a raw photo which actually contains enough information.
    b) know colour management to the nth degree so you don't screw it up.
    c) be able to edit it.
    d) have a perfectly colour managed process including softproofing.
    e) actually are willing to pay through your arse to get an incredibly high quality print. or have already paid through the arse to get an incredibly high quality printer.

    This criteria fits 2 photos I took in the last 3 years, and if you keep the RAWs like many people do (or archive in DNG like Adobe recommends) you can always go back and re-edit your picture using ProPhotoRGB if you need to. Otherwise it's a waste of effort.
     

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