If you are looking to do something like this above, I have found a script to do exactly that. It's pretty simple other than you need to find the right settings in the dialog box that will work for your image. There is an undo for the script but it's just easier to delete the layers if you don't like the results. Gimp can be fussy on "lesser" machines, so if your computer gets laggy from Gimp, back out of the script by deleting layers or simply closing out the image and starting again.
I've just discovered the script today (even though it's not new) and have only used it twice. I'm pleased with the results. Hats off to the writer of this script, whoever you are (the site doesn't give his/her name).
It's a great script. To "install", see the link above left on installing scm files. I am using Gimp 2.2.1, and I found the script in Filters> Artistic> Obama Hope. It is not under script-fu.
I mentioned settings. There are several to tweak but there's also the ability to change colors. This script is similar to the cutout script except that it recolors the image and also adds a stripe layer (not seen in the image above).
To get the script, go to the Gimp Registry Blog here. The download is under the word "attachment" in a grayed box. Find it in your downloads folder and copy/paste to your script folders (I put it in both found under User> Name> .gimp and Program Files> Gimp> etc etc etc.).
[Image Source: Google, a joke in reference to Clint Eastwood talking to an empty chair at the RNC in late August 2012.]
You can copy the images below so you can try it for yourself. You results might not be exact as mine because I changed the opacity settings on some of the layers. Layers 1-7 were all 90-100% opacity on overlay mode. Layer 8 was on normal and about 75-80% opacity. Layer 9 is my base image (background layer).
To do this: Open up your base image or in the case of mine above, bucket fill the background on a new image. For digital scrapbooking, the resolution is at 300 and dimensions are 3600x3600 pixels (my examples here are smaller to save my storage space on blogger).
Once you have the background image, in the image box go to File> Open As Layers> Select the images you want to import. After they load, save your new image as a psd or xcf file just in case there's a problem later.
Then select each layer one at a time and change the layer mode from normal to overlay. Click the eye next to each layer to see what your image looks like without the layer. Also change the way it looks by changing the opacity of each layer.
I've used brushes and erasers on selections of layers in the past. You can add text, making the text layer burn into the image by using layer modes and opacity. Experiment. When you find something you like, flatten your image and save as a jpg. In the quality box that pops up, I always select 100 (default is 85).
**You might have to change settings in your preferences (Tools box> File> Preferences> Environment) to accommodate the larger image with so many layers. I have my "Resource Consumption" settings at 100/100/150/150 and I often clear my undo cache in the dialog box but don't do this unless you know you don't need to back out of some of your changes in the undo levels.
[I hope you understood all of this. Seems whenever I'm doing tutorials I get interrupted 100x.]
I have a lot of new readers and some of you are new to Gimp. To understand some of what I am referring to, I will on occasion add some basics so you can keep up. The image above is one of them. I have labeled the screenshot to reflect what I call what in Gimp, which may or may not be what it's called in other tutorials. Over time, things change and people with other skillsets do tutorials. They may use terms from other programs, or in my case, give them nick-names of sorts. Now that you know the "what-where's" of my 3 most commonly used terms, you should have no trouble finding the rest of the buttons.
Of course you want your photos and graphics to be true color, and if you print, you want them to look good. You want your whites, white and your grays, gray. In order to prevent having an unintentional tint to your project, you should calibrate your monitor. Have you ever wondered if your editing is correct, in the case that someone else on another computer is seeing your artwork the way you intended? I always have and I finally found the answer.
I'm on a Windows PC, running W7. I wouldn't know how to do this on a Mac. Go to your control panel and in the search box type in "calibrate monitor". You'll get two results. Click on "Calibrate display color" and simply follow the instructions. There is a back arrow in the upper left in case you need to return to a previous screen. If you are not sure of the gamma setting in the beginning, use in tandem with Quick Gamma (a free download). Have your control panel window off to the side and Quick Gamma on the other, and you can see the change in Bar A on Quick Gamma. It says to have the gray bar disappear at 1.8 and still gray at 2.2 to be close to accurate. I then closed QG since the control panel was easy enough from there on. If you're on a laptop, your brightness controls are most likely on the keyboard.
Save your settings and continue on to the text adjustment. I highly recommend this as well. You probably thought text looked fine until you sharpen it with this tool. It does effect your images a bit too.
My only issue with calibration is that I do use my computers for other things, like streaming television and games. I tend to mess with the brightness almost daily. I was told to use the limo tint that comes in sheets like window clings since my screen doesn't get hot when in use. I'll have to give it a try. I'll update this post if I see a problem. A screen guard isn't practical for me on either of my computers and are much more money than a roll of limo tint from the auto parts store (I also was told to make sure it's non-adhesive, only clingy).
Have you ever wanted to make a photo go from color to black and white, as in a gradient loss of color? This tutorial will show you how. I used this awful photo here because the color of it is amazing. At the bottom of the tutorial is one photo you can click on and copy with complete visual instructions.
I did this tutorial with Gimp 2.2.12 but it should be nearly identical in other versions of Gimp as well as in Photoshop.
Start Gimp and open up the image you want to fade. Do any flaw editing and color enhancing now and save the new image. Be sure not to overwrite your original image in case you'll need it in the future. Duplicate the image in the layers box and select the upper layer, leaving the settings at normal and 100.
The upper layer should automatically have an alpha channel. You can check by going to Layer> Transparency> Add Alpha Channel. Since there already is one, it's deselected (grayed out).
Then click on Layer> Mask> Add Layer Mask.
A box will pop up, select Layer's Alpha Channel. Hit Ok.
Your layers dialog box should now look like this. Keep settings at normal and 100. Make sure you are still working on the upper layer.
Pick your gradient tool. Foreground (FG) should be white #ffffff and background (BG) should be black #000000. Opacity should be at 100 and mode normal. Reverse checked or unchecked is up to you. I'll cover that in a second. Click the Gradient box and make sure FG to BG (RGB) is selected. To dismiss, click off in the menu box anywhere. I also have my setting at Linear, other settings I'll cover at the bottom of this tutorial.
Click and drag your gradient "brush" across your image as in the example below. You can also go corner to corner for a different effect (the blue dots on the big image at bottom of this tut).
Look in your layers dialog box, it should look like the one below. Where the gradient is white, the image will be in color, where it's black it will desaturate (black and white). If this is not what you want, hit undo, return to your gradient settings and check or uncheck the reverse box and reapply the gradient on the top layer.
Your image is still in color, this is okay. Go to the layers dialog box and select the bottom layer. In the image window select Layer> Colors> Desaturate. Now your image should show the gradient fade.
Flatten image and save. Be sure to rename your image so you don't overwrite your original.
The photo below has two techniques added, this tutorial and the tut I posted just before on enhancing fall photos. Instead of using linear in my gradient settings I used radial, but you can get a similar effect with bilinear. Placement takes a lot of trial and errors. Remember where you start and stop your drag by using your photo as your guide. For instance, I had to use the right edge of the tracks where it goes from land to trestle and drag half way into the woods to the right. It's odd that the white part of the gradient ended up being to the left, but that's how it works, thus having to play with it. You might want to save as a psd or an xcf file before playing so you can go back if you need to.
Another thing to take note is in case your image keeps a small portion colored that doesn't look right, in my case the trees had excessive blue around the tree limbs in the sky, so I went to my layer mask layer and brushed on black in those places and it disappeared.
When I got my color how I wanted it, I flattened my image, then created a new layer, set to overlay mode and bucket filled with my favorite dark brown tint. I moved the opacity until I liked how it looked. Using dark brown did darken my image, it also warmed it up.
The whole tutorial in a single image with pink guide dots is below. Click on the image to get a larger version of it and save picture.
First off, my example photo is horrid. It's what I get for having one finger on my shutter and the other hand on the wheel. I have photographer's ADD. Anyway.... fall is just around the corner and shutters will be going crazy over the beauty of a colorful maple.
Sometimes simply hiking up the contrast on a photo won't do. Then you try the "copy layer, change to overlay" method and that doesn't do it for you either (especially if it washes out your sky - turning blue to white). There are other tricks. Of course there are filters but I like teaching the manual way because sometimes a filter can't be used or just doesn't fit your project perfectly either.
In the original photo above I didn't need to pull out the blue hue using levels. The color was realistic, just without the pop. I also took it into a 3 hour drive through a bug-spattered windshield, so I did some cloning. Always do this kind of "repair" to a photo before you color edit. Color editing occasionally will make unseen flaws come out so keep that in mind too.
Now that you're happy with your photo and all it needs is color, we will tint! Experiment with black and white as well as earth tones in your photos. Black makes a more dramatic shading than brown does, sometimes too much or it's just wrong for the composition. Brown is subtle, warm and blends nicely. I gave you the color blocks of the two browns I use for my gradients in the image above. Since my photo had the same lighting from top to bottom I only used the brown in the top layer, setting layer mode to overlay and sliding the opacity until it was perfect. In some of my fall shots, the trees tend to be dark if they are turned away from the sun, so I'll use linear or bi-linear gradient to lighten and warm these colors. You might have to keep reapplying the gradient several times until it's to your taste, so have your layer in overlay from the beginning.
*NOTE: If you are using solid colors in your gradient you can just redo your gradient, you don't have to hit "undo" to delete what you just did. If you are using one color and a transparency, you'll have to use undo. Experiment and you'll see why.
**If you are unsure of where to find these buttons, check on my labels in this post to find other posts where I cover the same subject. One of them shows the layers box.
There is a script-fu for creating an antique look called "old photo". Sometimes you might not want all of that noise, despeckling and border. The color might not be the best either. I have found the color above is the one people tend to like the most when I do color editing. The way I tint is a simple method using layers. Do your required editing to your photo, flatten and desaturate (the color on the right). Create a new layer, set on overlay. Bucket fill with this color. If you want it darker or lighter, maybe a slightly different hue, just use the hue-sat tool. Flatten and save. Don't forget not to overwrite your original.