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 Post subject: G'MIC Frame Trick
PostPosted: Wed May 22, 2013 12:01 pm  (#51) 
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Quick G'MIC frame with a nice extra touch.
1. G'MIC | Arrays & frames | Frame [regular]
2. Frame parameters: w=2, h=2
3. Change Output mode... | New active layer(s) | Apply
4. Frame parameters: w=8, h=8 | OK

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 Post subject: Re: Gimp Tips and Tricks
PostPosted: Sun Jun 02, 2013 7:07 am  (#52) 
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This was originally posted by smithaa02 - see viewtopic.php?f=23&t=7410

**************************************************************************
I thought it would be nice to put together an overview of the techniques you can use to fix or enhance brightness or contrast in an image. Feel free to suggest your tricks!

1) Colors > Brightness/Contrast. Very basic. Many times this is too all or nothing though.

2) Colors > Levels. One step more advanced. Often times is sufficient to do most basic corrections. Usually you'll want to drag the end arrows in to remove dead-space on the histogram and then play with the middle triangle until you get a nice look. Cropping some of the histogram is usually ok...but not too much.

3) Colors > Auto > Normalize. This will stretch the histogram to destroy deadspace to provide nice white balance and won't destroy any color data. This is usually very safe and a precursor to other operations...but often times it is too passive.

4) Colors > Auto > White Balance. Unlike normalize, this will chop weak data to provide a nice white balance. Sometimes this works well, but sometimes it doesn't. It also corrects color as well. I believe this is the same operation as Colors > Levels > Auto. Generally speaking I prefer manual levels over the auto functions unless I need to do batch operations (one of the major gimp batch plugins supports auto levels).

3) Colors > Curves. One step more advanced than levels. Through repeated sampling and adjusting you can more precisely control the shadows and highlights. Downside like levels is that this can be too all or nothing.

4) Using selections. This is a powerfull technique for brightness/contrast fixes. If I take a picture into the sun, no doubt I'll have exagerated highlights and shadow. Using curves/levels will not let me say restore detail of say a dark raft in the shadows without ruining the surrounding water and sky. Selecting the raft first, and then doing basic color operations on just the selection (like white-balance with levels) can produce VERY nice results. Downside is that it can take a while to make nice selections.

5) Filtering color corrections using HSV layers. If you duplicate your base layer and put it at the top with layer mode set to either Hue, Saturation or Balance...then those respective attributes will be protected. This is often handy when doing brightness tweaks, and you want to protect Saturation or Hue. Dupe layers for these...and then set one mode to Saturation...one to Hue. You can then see if that helps. Using protection layers is applicable for nearly all the techniques discussed here.

6) Overlay mode + duplicate layer. Overlay mode for layers provides more contrast. If you don't have blownout highlights or hidden shadows, this can be a very nice way to provide 'pop' to your picture. But if you do have shadow/highlight issues, this can exagerate those problems. Soft-light is a less mild version of overlay. Overlay mode can negatively affect colors though. It can be benificial to put a another layer ontop set to 'color' so overlay only affects brightness.

7) Contrast Mask. The idea of a contrast mask is to reduce blownout areas while similantously brighten under-exposed shadows. This is a very effective technique for a lot of amature outdoor shots. Nice tutorial at: http://www.gimp.org/tutorials/ContrastMask/ In a nutshell, you duplicate a layer, place it on top, desaturate it, invert it, blur it (like like radius 10px), then set the top layer to overlay. Normally overlay increases contrast, but because the brightness is the opposite, it decreases it. If your picture doesn't have shadow/highlight issues, this can unfortinitely make a picture look less 3d and more flat (you are reducing contrast after all).

7a) While most contrast mask plugins didn't recreate the same look as the manual technique describe above, the closest and best IMO is FX foundary > Photo > Enhancement > Contrast Overlay (I like blur = 10 and opacity = 100%)

8) Luminosity mask. These are apparently legendary and I'm still trying to figure them out. The gist is that you sub-divide a picture into say 2-5 selections based on lightness. You then perform curve corrections separately on each selection or mask. Great way to protect say a sky while adding that detail back into the shadows. Core concepts here: http://goodlight.us/index.html This is a very popular technique with nature photography.

8a) Obtaining tonal regions using thresholds and layer masks. In theory this should work, but I get banding issues.

8b) Generate the luminosity masks using this tool: http://registry.gimp.org/node/25479 Not bad, but seems to lack the ability to make more fine masks.

8c) G'mic > Enhancement > Mask Creator . Seems to be powerful and there is a nice example at http://www.flickr.com/groups/gimpusers/ ... 890498_281 ...but I just can't get a handle on this.

8d) Manually using desaturation/invert/difference layers. Nice but only gives you three tonal selections. http://gimpforums.com/thread-luminosity ... mp#pid5807

9) Tone mapping. Tone mapping basically reduces global contrast, while increasing local contrast. This is often times perfect! Example, I take a picture in the woods...normally the sky is overexposed and the trees underexposed. This balances the sky and gives it a nicer darker blue. Then it brightens the forest flow, but keeps local contrast so say the bark on the trees really stands out. Great trick!

9a) Think gimp comes with a tone mapping filter, but wouldn't recommend it

9b) Advanced Tone Mapping Plugin: http://registry.gimp.org/node/5980 Very nice. Similar effect to a contrast mask...but perhaps doesn't recover as much detail from the shadows and doesn't add as much in saturation.

9c) This is a different variant that is manual but allows for some nice tweaking. I liked the results. http://www.youtube.com/watch?v=FMlKVDjJFfY It provides a little bit more saturation then the other tone mapping techniques.

9d) G'mic has a nice one. G'mic > Colors > Tone Mapping (lots of options)

10) Shadow recovery. Filters > Eg > Shadow Recovery. Not bad results for taking on shadows.

11) Use mid-tone selections for levels/curves to protect the extreme black/white ends of your picture. Often times you just want to bring out the detail in the image without messing up the extreme dark and light portions of the picture. Duplicate your picture and use an auto-normalize, to apply a quick but safe white-balance. Right click the top layer and create a new layer mask from a grey scale version of that layer. Edit the layer mask with curves to give it a pulse shape (0->255->0). This will now only select the midtones of your top layer. Now select the top layer itself (not the mask) and play with levels/curves. You can now increase the contrast of the midtones safely.


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 Post subject: Selection Tool: Highlight and Guides
PostPosted: Mon Jun 17, 2013 12:18 am  (#53) 
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Often overlooked, the two Selection Tool Options, Highlight and Guides.
[Tip] Both Highlight and Guides can be added and toggled after selection.

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 Post subject: Measure Tool & Guides
PostPosted: Mon Jun 17, 2013 1:40 am  (#54) 
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Create guides at the Measure Tool end points.
Ctrl + Click, horizontal guide.
Alt + Click, vertical guide.

[Tip] Handy when using the Perceptive Tool.

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 Post subject: Re: Measure Tool & Guides
PostPosted: Mon Jun 17, 2013 2:17 am  (#55) 
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Odinbc wrote:
Create guides at the Measure Tool end point.
Ctrl + Click, horizontal guide.
Alt + Click, vertical guide.

This is the Cool Tip of The week but... adding the horizontal guide works for me, but not adding a vertical one (but when I depress the Alt key, I get a lateral arrow head... ) Am I alone in this case (2.8.2 on Linux)?

And now, the big surprise, Alt alone doesn't work, but Ctrl-Alt-click creates both vertical and horizontal guides!

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 Post subject: Re: Measure Tool & Guides
PostPosted: Mon Jun 17, 2013 5:08 am  (#56) 
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ofnuts wrote:
This is the Cool Tip of The week but... adding the horizontal guide works for me, but not adding a vertical one (but when I depress the Alt key, I get a lateral arrow head... ) Am I alone in this case (2.8.2 on Linux)?

And now, the big surprise, Alt alone doesn't work, but Ctrl-Alt-click creates both vertical and horizontal guides!

Your window manager probably already has a function assigned to the ALT+click combination (KDE and Gnome use it for moving windows). If this is the case, you should be able to use ALT+SHIFT+click to create the vertical guide. Alternately, you could reassign your window manager's trapping of the ALT key to some other key (e.g., the "windows" key or a combination such as ALT+CTRL).

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 Post subject: Re: Gimp Tips and Tricks
PostPosted: Mon Jun 17, 2013 5:41 pm  (#57) 
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A trick that was mentioned recently in the developer's list. When you use the brightness/contrast tool, you can click in the picture and move your cursor to do the adjustments, a vertical move changes the brightness and n horizontal one changes the contrast, and of course diagonal moves let you adjust both at the same time.

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 Post subject: Re: Gimp Tips and Tricks
PostPosted: Sat Jun 29, 2013 9:49 am  (#58) 
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Image in-session size indicates how much memory is being allocated in gimp swap space on your hard drive
(it is usually a lot bigger than the real size of saved gimp document)
It's shown in the information panel on the bottom of main window

Image


When working on your image info panel displays only active tool tips and image size is not shown.
You can bring up image size info to the Image title bar (on the top of main menu) - so it's never hidden.

Image

All you need to do is to add (%m) to the Image Title format line in User Preferences.
No need to restart gimp - it will appear right away.

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 Post subject: Easy Gimp Splash Screen
PostPosted: Thu Aug 01, 2013 3:04 am  (#59) 
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Easy Gimp Splash Screen
1. Make a graphic 557 x 346 px
2. Add vertical guides at, 160 & 380 px
3. Add horizontal guide at, 280 px
4. Start up text shows in the middle bottom area marked by the guides.
5. Export as, splash-screen.png. (multiple splash screen files will load at random) *
6. Save in [user_name] splashes folder.
  • Linux: /home/user_name/.gimp-2.8/splashes.
  • Windows: \user_name\.gimp-2.8\splashes

Image

* Splash Image(s) Loading Order
Customize Splash-Screen
GIMP Splash Archive

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 Post subject: Surround Selection Trick
PostPosted: Mon Aug 12, 2013 4:29 pm  (#60) 
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The quickest way to surround select text.
1. Layers Dialog, Right click text layer, Alpha to Selection.
2. Select | Grow selection (type size).
3. Select | Shrink... (optional).
4. Select | Save to Channel (optional).

This technique can be useful removing errant pixels selected within a larger selection.

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