Hello friends,I am going to convert a image with one dominant color into rainbow color images.you can do this for any kind of image.I selected a red hibiscus image for this editing.,then I convert the image into rainbow color image using GIMP(GNU image manipulation program).It is an open source image editing program with powerful features.

Supplies

GIMP SOFTWARE - download it only from the official website.

Step 1: HUE-CHROMA ADJUSTMENT

We can able to change the colors in several ways,First we are going to see the hue-chroma adjustment.

open the GIMP software
click on the 'colors' on the tool bar that is in top of the screen.
Select Hue-Chroma from the drop down list
a dialog box opens
you will see a bar Hue adjustment.
using the slider change the colors.
save the image after you get the desired color every time.
YOU CAN ADJUST CHROMA & LIGHTNESS SLIDERS FOR MORE RESULTS like one of the image.

Step 2: Colorize Option

Here also the same dialog box opens with an addition of color bar for more adjustment.
click on the color bar, a new dialog box will opens
here you can choose the depth of colors and other adjustments.
you can adjust the color and it's depth by GIMP,CMYK, water color ,wheel,pallette..they are situated over the color section box in the form of small icons.
save the imag ,after you get the desired color.

Step 3: Other Options

you can also play with the options in the color list.

adjust the sliders very slowly in color temperature option as it provide any one color change depends upon the original color of the image .but you can adjust the temperature of already changed(color) image.

NOTE: only download GIMP software from the original website as it is an open source software.