In this tutorial, we'll colorize an image that has a consistent pattern with equal colored parts and white/neutral parts, such as gingham or plaid. Since this is basically a technique that can be applied to a wide variety of images, I'll just use a plain square of scanned gingham material.
Technique step 1

I used this technique in my last two colorization entries “Dorothy Gale” and “Bessie in the Kitchen” - check them out to see the colored & neutral ginghams in the context of a whole image.

This is the original black and white scan:

The first step is to create a hue/saturation adjustment layer by clicking on the icon in the bottom of the layers palate that looks like a half black/half white circle. Choose hue/saturation.

In the dialog box, click “colorize” and slide the hue slider to the left to a green shade; slide the saturation slider to your desired saturation; leave the lightness at zero and click “OK”. Now with the adjustment layer active, change the mode from “normal” to “color” in the drop-down box at the top of the layers palate.

We have a nice, bright patch of gingham. Problem is, the lightest squares have a green tint as well. Real gingham doesn't have a strong color tint in the light squares.


Technique step 2
To solve this, the first step is to adjust the blending mode of the green hue/saturation layer. You can access the blending options dialog quickly by double clicking on any gray area of the layer in the layers palate. Another way is by clicking on the icon at the bottom of the palate that looks like a black circle with a cursive “f”.

In the blending options dialog, locate the “Blend If” options at the bottom. We only want to color the dark parts of the underlying gingham layer, so slide the white slider to the left. This takes out the green in the light parts, but it's choppy and abrupt. To fix this, hold down the alt key and click one side of the white slider and drag – it splits into two halves. The further apart they are, the more gradual the blend.

Here I've set the left side to 120 and the right side to 200.
To get this result:

Technique step 3
We still have one more step, because the white squares look too dull and gray. So create a second hue/saturation adjustment layer, again clicking the “colorize” box. The hue we pick will be the complementary color to our base color, because it will balance out to white. For green, the complementary color is red, so slide the hue all the way to the right. Lower the saturation quite a bit because we don't want pink squares, we want white/neutral. Leave the lightness at zero and click “OK”. Change this layer's mode to “soft light”.

Now, since we only want the light squares affected by this adjustment layer, open the blending dialog box and this time slide the dark sliders to the right. Again, split them using the alt key while clicking & dragging one side of the triangle.
Here, I have the left side set to 140 and the right side set to 200.

Here's our final green gingham patch with nice neutral background squares:

Red Variation
This page and the next will show red and blue squares using the same exact techniques.
Red hue/saturation adjustment layer:

After adjusting the blending sliders on the red hue/adjustment layer:

After adding and blending the complementary green/cyan hue/adjustment layer for the neutral squares:

Blue Variation
Blue hue/saturation adjustment layer:

After adjusting the blending sliders on the blue hue/adjustment layer:

After adding and blending the complementary yellow hue/adjustment layer for the neutral squares:

Orange Variation
This page and the next will show yellow and orange gingham squares. The technique is basically the same, except that we'll change the mode of both hue/saturation layers to “hard light” instead of “color” and “soft light”. You might find that the first step alone is sufficient since the light modes don't transfer color information to white areas. But if it is too saturated or blown out, either adjust the saturtion sliders or add the complementary hue/adjustment layer.
Orange hue/saturation adjustment layer:

After adjusting the blending sliders on the orange hue/adjustment layer:

After adding and blending the complimentary greenish blue hue/adjustment layer for the neutral squares:

Yellow Variation
Yellow hue/saturation adjustment layer (remember, set this and the second hue/saturation layers to "hard light"):

After adjusting the blending sliders on the yellow hue/adjustment layer:

After adding and blending the complementary blue hue/adjustment layer for the neutral squares:

I hope you'll find a variety of uses for this technique in your images besides gingham - such as plaid, striped or polka-dotted patterns.