Episode 131: Automatic?

Aperture 1935Download the Video! (57.9 MB, 30:27)
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After a bit of “housekeeping”, which includes thanks to contributors and a nod over to the Focus Ring, I try to use the stuff hidden in the <Image>/Color/Auto menu. My results are not that good and I try to do it better with curves.

Why did I fail? No idea, it may be the software or perhaps my choice of image was bad. Please share your experiences with this option.

At the end of the show I lift the secret behind the numbers 1 – 1.4 – 2 – 2.8 – 4 – 5.6 – 11 – 16 – 22 …. – aperture numbers decoded.

I couldn’t decide which of the two shots I made for the show image should go into the post, so here are both. :-)

Aperture ca. 1980


00:20 Starting 2010 – thanks and a guy selling GIMP
04:30 New Forum policy
05:40 New Focus Ring Episode
07:00 Exporting an image from F-Spot to GIMP
07:20 The Histogram shows underexposure
08:00 Exploring /Colors/Auto
09:15 Equalize, stretch contrast, stretch HSV
11:50 Color Enhance
12:50 The manual curves approach
15:30 Unsharp Maks (USM) for getting details in snow
17:00 Selection with layer mask
19:00 Basics: Apperture numbers explained

Creative Commons License
Meet the GIMP Video Podcast by Rolf Steinort and Philippe Demartin is licensed under a Creative Commons Attribution-Share Alike 3.0 Germany License.
Permissions beyond the scope of this license may be available at http://meetthegimp.org.

19 thoughts on “Episode 131: Automatic?

  1. in iTunes ist diese Folge leider nicht verfügbar.
    Die letzten Folgen werden nur noch in HD Qualität gesendet? Schade, denn ich hatte die Episoden immer auf meinem iPod und bei Bedarf diesen am Fernseher übertragen. Das geht nun nicht mehr??!!

  2. Both should be fixed now. Permissions were set wrongly, no idea why.

    I can’t render a mobile version at the moment because Ubuntu Karmic doesn’t support the codec. If someone knows a way to render for iPod under Karmic, please tell me.

  3. As always a great episode it was verry interesting learn a lot from it.
    It’s a shame that you must check new members so you do not get any junk on the forum.

    Thanks a lot and keep up the great work.

  4. Brilliant episode the photography stuff recently is a great addition really enjoying it even if I do understand the concepts its always a great resource to jog the old brain box :)

  5. Thank you for the nice explanation of aperture.
    Concerning your handling of the snow I have a different opinion. You reduced the incline of your curve where you have all the nice contrasts in the snow. So you needed to do some unsharpen manipulations. This only results in artifacts. You should instead try to increase the steepness of the curve in the white tones.
    In my workflow I handle this with the white balance of the RAW. Personally I use DxO, but if you prefer open source, UFRaw would certainly be able to do the job. With RAW you wouldn’t have trouble with this 8 bit rounding artifacts.
    For me doing manual white balance is the first step for every picture with a somewhat tricky lightning situation such as snow.

  6. Good thoughts! I’ll give it a try.

    Normally I would have used the RAW image too, but I wanted to show how to handle the situation in JPEG. So I’ll tackle another snow image from that session in the next show.

  7. Increasing contrast by white balancing? That’s something you have to show or explain in more detail. I can’t imagine how this should work…

    And increasing the steepness of the curve in the bright snow areas is ok to increase this local contrast. But the whole image will look underexposed and flat – increasing the steepness of the curve at one point decreases it at another.
    So in my workflow USM is indeed the most suited solution to enhance snow details. If it’s really tricky, I do increase the steepness of the curve for the snow but use a layer mask to only effect the snow whereas the rest of the image remains bright and contrasty.

  8. Mathias, I don’t want to increase the contrast by white balance. But the way Rolf handled the photo he decreased the contrast in the most interesting part – the snow. But obviously the white balance wasn’t good in the beginning. I think curves tool is not the best way to fix this. So first get the white balance right and than increase the local contrast with the curve tool. If you still need USM you can do so. In the case of Rolf’s photo I don’t think it would be necessary.

    In the case of the snow photo a decrease of contrast within the trees wouldn’t matter. You have the maximum possible contrast there: black – white.

    Rolf: With JPEG you have do use a lot of tricks, which aren’t necessary with RAW. I think we agree, you should use RAW for every serious work. But of cause you quite often get JPEGs from someone and you try to fix them. Then you need to know this tricks.

  9. Christoph: You are right with RAW of course, but a lot of cameras don’t have it – and this podcast should offer solutions for them too. And I am not the GIMP Guru, I am only the guy who puts out his head in the video. ;-)

    Paul: You have to differentiate between metering and exposing. You have to expose more than the metering is telling you. The metering assumes a medium grey image with a lot less light and so assumes that there is a lot more light than there really is. But check your camera, there may be some intelligent metering systems around that recognize snow. But I like to expose a snow shot less than a “correct exposure” would be. Then the brightest snow is light grey and I don’t have blown out highlights.

  10. hey nice episode this was.. :)

    i wanted to know which software u used to explain the aperture topics??? is it a caed/cad software??
    its name and website would be better.. :)

    thanx for all the great gimp tutorials :)

  11. Its nice today i got 100 episoed in a dvd thru open source magazine

    i will be glad if i get openoffice presentations or the way to embed video in openoffice,

    some more tuotials i am looking , i shortly refer your link to my blog fosscommunity.wordpress.com

    dediacted to FoSS software and community, i am thankful to you and the theam and their efforts for the community

  12. Pingback: MTG: Эпизоды 1 квартала 2010 « Блог фотолюбителя :)

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