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

This was originally posted by smithaa02 - see viewtopic.php?f=23&t=7410

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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.

Often overlooked, the two Selection Tool Options, Highlight and Guides.
[Tip] Both Highlight and Guides can be added and toggled after selection.

Create guides at the Measure Tool end points.
Ctrl + Click, horizontal guide.
Alt + Click, vertical guide.

[Tip] Handy when using the Perceptive Tool.

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).

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.

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

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

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.

This is very rudimentary, but I don't see anything
here, so you decide if this tip is any good or not,
after installing gimp, I Create several Templates.

File\Create Template
Pretty simple, pretty useful
_T_= transparent background

1920x1080_T_WDHDTV my desktop
1280X800_T_notebook brothers desktop
1080x1080_T_HDTV
1024x1024_T_clipbrd or gmic
512x512_T_gmic
256x256_T_L-thumb
50x50_T_DA
8x8_T_snap
1x1_T_mem-min

I know there's a tips and tricks thread some place around here but I'll be damned if I can find it.
Anyway, not sure if this has been mentioned before but I just found a way to enable Gimp to open RAW files without running them through a separate photo editor first. It's pretty straight forward, just install gimp-dcraw, I did it via synaptic on LM16, and them Gimp will open the RAW files for whichever folder they are saved in.
Just though I'd mention it.
btw, running Gimp 2.8.8 and Linux Mint 16.

Edit: someone found it for me, cheers for moving this.

Not a tutorial, just a hint inspired by an off-line question.

if your image is tiny (say 300x300 and not copyrighted)

step resize to as big as you can handle

gblur the unsharp as many times as needed

smudge, heal and touch up as needed

color enhance

when happy, step resize down to the required size.

Generally produces an exceptable result but tweaking and experementing may be required.

Hope it helps

For helpful color information.
1. Go to DuckDuckGo.
2. Enter color hex notation (e.g., #268bd2).
3. Select the Info link.



Alternative, ColorHexa.

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Bonus tip from, http://wiki.gimp.org/index.php/Users:Tips.

This "tip" is really just to share a dumb (i.e., erroneous) assumption I've been making for about a decade.

The right-most tab in GIMP's color chooser dialog shows a small assortment of useful colors. By default it shows the primary colors plus some simple combinations thereof (e.g., CMY), as well as various shades of gray.



I always thought these colors were hard coded, making the tab of limited utility. Turns out I was wrong and the set of colors shown in that tab is the currently active palette. When GIMP starts, the active palette is set to be the "Default" palette; switch to a different palette and you will have a different set of colors from which to choose.

One can move a text layer while editing it by holding down the ALT key and dragging (simple, I know, but I only just discovered this).

Handy YouTube keyboard shortcuts when watching tutorials.

Left / Right arrow => Jump back / ahead 5 seconds in the current video
Home / End ======> Seek to the beginning / last seconds of the video
Spacebar ========> Play / Pause
Numbers 1 to 9 ===> Seek to the 10% to 90% of the video (not the keypad)
Number 0 ========> Seek to the beginning of the video (not the keypad)
Up / Down arrow => Increase / Decrease volume 5%

Dragging a layer's thumbnail preview and dropping it on the New Layer button will create the new layer having the same size and location. There will be no dialog popping up and the new layer will be filled using the same Layer Fill Type as was used when last the New Layer command was run.

For example, to place a colored layer as a backdrop to a text layer, you could drag-n-drop the text layer onto the New Layer button, then click the Move Down button.

Thats cool Saulgoode, that would cut out a few steps.