Overlay data and colorize
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Contents: Description, Procedure, Functions Used
Description Overlay two data images using one to color the other. This example overlays day time Themis IR with colorized night time Themis IR of the same region on Mars.
Procedure Load in the two images: dv> day_time = read("day_time.cub")
279x300x1 array of byte, bip format [83,700 bytes]
dv> night_time = read("night_time.cub")
279x300x1 array of byte, bip format [83,700 bytes]
Display the data dv> display(day_time)
dv> display(night_time)
Colorize the night_time data dv> night_time_col = colorize(night_time) 255,000,255 = 0.000000 000,000,255 = 51.000000 000,255,000 = 102.000000 255,255,000 = 153.000000 255,128,000 = 204.000000 255,000,000 = 255.000000 279x300x3 array of byte, bip format [251,100 bytes] dv> display(night_time_col)
Create an overlay array. Add 50% of the color of the night_time_col to day_time. We chose a value of 50% arbitrarily, adding more will result in a picture with stronger color. We'll do another at 15% to show the difference. Davinci will automatically copy the 1-band day_time image to each color band of night_time_col*0.5 dv> overlay = night_time_col*0.5 + day_time 279x300x3 array of float, bip format [1,004,400 bytes] dv> overlay2 = night_time_col*0.15 + day_time 279x300x3 array of float, bip format [1,004,400 bytes] Now, because the overlay array may have values exceeding 255 if turned directly into byte, causing some pixels to be oversaturated, we sstretch the array, rescaling it from 0 to 255. dv> overlay = sstretch(overlay) 279x300x3 array of byte, bip format [251,100 bytes] dv> overlay2 = sstretch(overlay2) 279x300x3 array of byte, bip format [251,100 bytes] dv> display(overlay) dv> display(overlay2)
Additional Notes: There are an infinite number of options for combining the color of one image to the black and white of another. This is merely one option. As you can tell, this procedure trades strength of shadow for strength of color. |
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