So tonight I'm exploring rainbows. I want to see what I can do with a rainbow to bring an edge to a photo.

What I found is a technique that seems to be great for macro shots and any shot that is more up close. It works well on some images but not on others. The end result is a fun colorful photo.

Step 1: Step One Adjust Curves

So step one is a curves adjustment. Now this is usually specific to an image. I don't always follow the same pattern or method of adjusting curves. What I usually do is slide it drastically up and down, then adjust. Left side is your darks and right side the lights in your image. For this image specifically I did a standard s curve for value. darks adjusted down, and lights adjusted up. Making the darks darker and the lights lighter. For the reds channel I adjusted both the darks up and the lights up. When I say up I mean from the center line. So up would be above it. Then for greens I went down on darks and up on lights. For blue I went up on darks and down on lights.

Then I always readjust the value after I'm satisfied with the color adjustments. I find that sometimes you just need to readjust the value curve after you have adjusted color curves.

once I am satisfied with the curves adjustment I will apply it to my image. I always work on a duplicate of the image so that I can easily step back if I dislike an adjustment that I make. So I just right click and duplicate layer then make my adjustments.

If you follow the same pattern of adjustment you should end up with an image that has a slightly blue tint. This is because we added blue to both the lights and darks.

Step 2: Step 2 Adjust Saturation

My second step in editing a photo is to always adjust saturation. Sometimes if I'm wanting a cooler mood I decrease saturation slightly, Most of the time though I increase the saturation. The only exception would be for portraits. In portraits I always decrease saturation rather than increase it. Otherwise you end up with very funny skin tones that just don't look natural.

In the example above I increased the saturation. Again this adjustment is specific to the image. I play with drastically increasing it first then drastically decreasing it. I choose which looks better then adjust until it suits my tastes or the image.

So just play with saturation until you are happy with it. If you are following this exactly then you want high saturation. This technique also works best on images that are already colorful. but as you can see from my example it can be a plain image to begin with.

Step 3: Step 3 and 4. Gradient Map

So I love a vintage 70's era feel to my photos. So I always tint them purple using a gradient map. THis step is optional. If you aren't inclined to the feel of vintage photos or think that purple tinted images just aren't for you, you can skip this step altogether. I'm including it because I always add purple tinting to my photos.

I doubt I could give you a good explanation for this. Mostly its a color theory thing, I usually take photos where green is a major element in them, such as the grass and I think that the purple brings out the green better. But again this is my taste and individual addition to my photographs and may not be for everyone.

You can also play around at this point and add different gradients. Its up to you

The steps to adding a gradient map are as follows

First select your gradient, in this case I used purples, and make sure you are working on a duplicate of your last layer.

Next go to colors, maps, gradient map.

Once you select the gradients map option gimp will apply the gradient map without a window popping up.

Lastly set this new layer to soft light and adjust opacity to around 60%. Or rather between 20%and 60%.

That's it, the image now has a lovely purple tint to it that takes me back to vintage era films.

Step 4: Step 5 and 6 Contrast Adjustment

So I know we already applied a curves adjustment to the image, but I almost always increase contrast to an image by adding either an overlay or soft light layer of the image in greyscale. This is again something of an individual taste. It creates amazing texture which is why I do it. But it might not be to your tastes and can be ignored if you don't like it. Sometimes I use it. Sometimes I don't. It just depends on the image.

So what I did was desaturate a copy of my image (on a new layer) using the desaturate option shown above. I selected luminosity as the option to use. But again since this is to bring out texture you can play with the options and see which enhances textures most in your opinion. Once I was happy with my desaturation I set the layer mode to soft light and Reduced the opacity to around 50 %.

So extra contrast added.

Sometimes if I dislike how this looks at this stage I will add a greyscale copy of the layer as an layer mask and see if it works better. I also either set this to overlay or soft light. Most often soft light as the effect isn't as drastic.

Once I'm satisfied then its onto making the image more colorful.

Step 5: Color That Image

The last step is the step that adds the most color to the image. This is why it works best on an already colorful image. But it does work with plain images as well.

The only downside to this technique is that it adds a bit of cloud like texture to the image that is often visible in the sky of an image or the lighter areas of an image. So if the texture doesn't work then you need to use gaussian blur on the layer. Otherwise just follow my steps below.

On a newly created layer thats blank go to filters, render, noise, plasma. Leave the plasma dialog at their defaults and just hit ok.

Then set this layer to soft light and reduce the opacity until you are happy with the overall look of the image.