Episode 023: Colours, Colors and Dialogs

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GIMP offers you 9 different ways to select a colour for foreground and background. I try to make sense of them. Perhaps it’s a bit too long winded? Please comment on that here or write me a mail. I need YOUR input for thinking about where to go in the next year.

I have prepared some example images for the different colour modes. They didn’t made it into the show – but here they are anyway.

The image has been split up into the three RGB channels. Black is 0, white 255.

The image has been split up into the three HSV channels. You see, HSV may be more intuitive for selecting a colour, but the hue and saturation channel look very strange.

The image is made with a Nikon D70 pinhole camera. I drilled a hole through the body cap, covered it with aluminium foil and punched a pinhole into the foil.
Weser with old water tower shot with a pinhole

Some links:

Joel’s Blog “Linux Photography” and especially his stuff about colour management.

Wikipedia has a lot about color, colour temperature, visible light, colour spaces and more.

The Panorama Challenge is open up to Dec. 14 12:00 GMT.


00:23 Welcome
01:10 About colour
03:07 Colour spaces
06:40 Selecting colours in Gimp
07:05 – Scales
10:46 – Wheel
11:56 – Gimp
13:19 – Watercolour
14:15 – Palette
14:40 – CMYK
18:51 Foreground and Background colours
20:30 Colour Picker
21:40 Meet the gimp Photogroup on 23hq
26:28 The End
TOC made by paynekj

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16 thoughts on “Episode 023: Colours, Colors and Dialogs

  1. Hi Rolf,

    I’ve checked most of the episodes and have found them of great use, specially because they’re geared towards my level of knowledge, i.e., not a pro, but not a newbie, either.

    One thing I liked specially is that instead of simply explaining Gimp functions like in the manual, you have done so in the context of actually working on a photo, which makes it much more interesting and also truly helps one to learn, not just try to remember all the shortcuts and the functions.

    Now this last episode was the antithesis of all this, so, in my humble opinion, I give it a thumbs down: over twenty minutes explaining how to pick a color? For people who understand the basics of colors and working with pictures, it is unnecessary, and for newbies, it is useless, until they know what they’re doing.

    Don’t take me wrong, I love the show and urge you to stick at it, but I just wanted to give you my contribution in order for it to focus on what makes it special and really useful.

    Of course, there’s no such thing as an “all-around” useful tutorial, because what one person finds daunting, the other finds too simplistic, and the balance is therefore impossible to achieve for everyone, so take this opinion of mine as a data point, and let’s see what the others think.

    As for a suggestion of areas to explore in 2008, I think any post-processing work with different tools than the ones you explained already, would be a great fit.



  2. I learned a few new things here in this episode on colour. I think the really neat one is just having to type a letter and all the colour names come up from which you can continue your selection. Been messing with Gimp for years on and off and never knew this one.

    thanks and regards Pete

  3. Thanks to an announcement on the Hugin home page I discovered your podcasting show. It is a great way of learning; in fact, I was not aware of this until now.

    I would like to see some shows on post-processing with the Gimp; not a summary of technical possibilities, but rather the other way around: if one wishes a certain mood or effect, which possibilities are there to achieve that? This could be extended to compositing.

    On the technical side, an explanation of the layer overlay modes would be most welcome.

    Thanks and keep it up, Serge

  4. This episode is not one of the best, you (Bruno & Serge) are right there. ;-)

    I am thinking about a new structure for the next year. Perhaps different types of shows for different needs to fill.

    The “Walkthrough” with an image from start to end (like shows – but that gets repetitive soon I fear. One short will come up at Christmas.

    The “Concepts” like the layer modes explained in detail, wait for something like that at New Years Day. Well, it will be there at 19:00 UTC if my server got his clock right, but perhaps you have something better to do that day than waiting or it. ;-)

    A “Toolbox” series – two of them are ready to go up in January. There I’ll try to explain a tool or plugin in depth.

    Your posts got me thinking about a “Methods” type of show. A bit like the selective sharpening episode.

    And then some stuff I haven’t really thought about up to now or that doesn’t fit into one of the categories. The next one will be a complete mix of everything. Then 5 shows that I have already recorded and partly produced and while they run I’ll have time to make some better plans. And have a break….

    If you have any ideas – drop me a mail or a comment!

  5. One of the many things I like is that from time to time you produce a purely technical/scientific show. Whenever I tried in the past to produce colour prints on photographic paper I found it very difficult to get my head around the subtractive process and to have the HSV approach presented was a real eye opener. OK, perhaps one needs to use ones imagination on how to apply what you presented to post processing the digital image but, nevertheless, it is part of Gimp and very well worth knowing about.

  6. Hi,

    I have to say I have enjoyed every show so far and am looking forward to any future ones. I mostly enjoyed the walkthrough type shows but think the more technical episodes are just as valuable. I would be really interested in an in depth layer mode/ layer mask episode (or two!)

    Just keep a good mix as you have been doing and I’ll be happy ;-)

  7. Rolf, it’s good you’ve given technical background information.
    To understand why we do thinks,
    To know what theoritical reason there is,
    all helps us when we practise en skill ourselves.
    A dutch saying is: You can learn a monkey a tric.

    And we know we’re humans. We can learn a monkey a tric. But before that we have to know how something works and how we’re able to reach a goal.

    Keep going on

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  9. I have some more information about colors
    I really mis CMYK support in GIMP as CMYK is used in professional environments

    CMYK = cyaan magenta yellow and key (key for key color) [Actually Cyan magenta and yellow should all make black together if they are mixed. Pigments in paint/inkt just aren't strong enough so there is a extra key color witch is black]

    RGB = Red Green Bleu
    RGB = mixing light (add a red light bulb and a green light bulb and shine them together and you get yellow light(all of them together make wite light).

    RGB and CMYK arent that complicated and to show that, someone invented color circles.

    RGB color circle

    CMY(K) color circle

    If you compare the 2 circles you see they are just the opposite of each other.

    When the RGB light is mixed you get the CMY colors in the lapping point

    When you do the same with CMY(mixing them) you get RGB colors.

    The big difference is the way of mixing them as RGB works with light and CMYK with inkt
    It is of course a bit more complicated as i explain here but in the big lines this is rgb and cmy(k)

    I don’t know if i made this clear enough as my English is a bit blurry

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Anything to add from your side of the computer?