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This is the fastest method I know for changing the color of something in a picture using GIMPPortable, or Photoshop. You make a hasty selection with the lasso tool, feather it, and then adjust the hue, using the option to adjust only the blues in the picture. This prevents unwanted color changes simply.

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GoodCleanCrazy

Step 1: Make a Quick Selection

Open your picture in GIMP.

In my picture, I want the blue car to be green, but not the carpet, or anything in the background, so I need to roughly select the car.

Click on the lasso tool. Drag a quick selection around the car. Tweak the selection a bit using to add to the selection and to subtract from the selection. You do not have to be perfect with this. Not even close.

Great. Car selected.

Step 2: Adjust the Hue

Go to Layer>Colors>Hue-Saturation

Select the blue swatch in the Hue Saturation window that pops up, and drag the hue slider around. Pretty good. Click OK.

Let us take a look at our picture without the crawling ants. Hit or go to Select>None.

Now I noticed a slight line on the floor near the selection edge. This is because there is a little blue light hitting the floor.

We can fix that by feathering the selection before adjusting the hue.

Step 3: Feather the Selection

Go back a few steps with or by going to Edit>Undo a couple times until you see the original picture with a selection.

Now go to Selection>Feather and change the value to, say 10 pixels. Click OK.

Adjust the hue again and look at your final picture. No line near the floor. Great.

Save your new picture.

Step 4: A Final Note

One final note on changing the hue of something in an image: In nature, some colors appear more saturated than others. So when you change a hue, tone down the saturation a bit to see if it looks more realistic.

So the steps again are:

1)Rough selection.

2)Feather the selection.

3)Adjust the Hue.

Happy shopping!
here mine hope you like it
This is mine.
The first pic was red and the second was dark blue. these images were from google. GREAT INSTRUCTABLE!!!!!! you can do this on any computer with gimp portable!
Hey, good job.
You could use this techniqe for background subtraction on still images.
How's that? I know of a few background subtraction techniques but one using a hue adjustment is news to me. Care to share?
Or maybe I was wrong I tried it later and it didn't work. Sorry :D
nice to see how everbody uses your instructable for new instructables. but you can also download the normal version of gimp on www.gimp.org!!! it works alot faster!
Who uses my instructables for new instructables? Anyhoo . . .I'm going to check out the new version of GIMP now.
his bag is not green
hah, you misunderstand the effects of GI. or global illumination. If you look at the picture of the blue car, his bag is tinted blue thanks to the reflected light. He did this quite right, sorry asianwizard ;p.
You know, I didn't even notice the bounce light on the bag. Sharp eyes y'all!

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