A tutorial for Photoshop using a couple of layer blending modes.

Before	After

Have you ever tried to photograph a rainbow?  It's not too much of a problem except it always seems that when you see one there is never decent backdrop. I have tried various Rainbow glass filters in front of the lens, but never with any degree of success - they just look naff. I am going to show you how to create a rainbow on your own desktop and apply it to an image (pot of gold not included). A picture with a darkend sky works best.

Gradient tool & sample	The Gradient Editor

Click on the Gradient Tool and then click the gradient sample on the Options toolbar, this opens the Gradient Editor. Select the Transparent Rainbow swatch and follow these next steps carefully.

Step 1.

Delete the four black stops on top	Change the end stops opacity to 100%

Delete the four black opacity stops on the top of the gradient, then change the opacity of the two white end stops to 100%, they will now turn black and all the colours will be visible.

Step 2.

Add two black stops at the bottom	Move the sliders

Add two extra stops underneath the Gradient bar, ( click the mouse under the bar to add a stop), position their locations at 0 & 100%. Double click on the new stops and define their colour as black. Next, starting with the Magenta stop, drag the stop to the right and place it at location 98%, the Blue to location 96%, Cyan to 94%, Green to 92%, Yellow to 90% and Red to 88%.

Step 3.

Add an extra Black stop...	and position this Location at 86%

This next step is important, the gradient will have a large area of Red (the last colour) so you must add an extra black stop to stop the red. Click beneath the gradient to add another black stop between the red and the end black stop. Move this new stop to Location 86%. You should have a new gradient that looks like the sample above.

Step 4.

Save your new Gradient

Give your Gradient a name and save it for repeated use at a later date.

Step 5.

Create a new layer	Drag out a Radial Gradient

Create a new layer and set the layers blending mode to Screen. Using the new layer, select the Gradient tool and select Radial Gradient on the Options toolbar. Click on the centre of your image, drag the Gradient down to the base or beyond of your picture and release the mouse. You should have a picture that looks like the above sample. If it doesn't look right then drag out another Gradient, this replaces your previous Gradient. Use the move tool to adjust positioning and use the eraser to remove unwanted parts of the rainbow. On my final shot I also erased parts of the rainbow which crossed over the wheel, your picture might not have a object that dominates the sky-line.

Things are never Black & White.

Before	After

Staying with the Gradient fill and using a similar technique you can add colour to a monochrome image. Open a B/W picture and change the Mode to RGB Color, create a new blank layer and set the blending mode to Overlay. Click on the Gradient tool, click the Sample swatch and select a Gradient. Set the Gradient mode to Linear and drag out a gradient, simple.

Something I made earlier.