Making 2-color-band Images In Photoshop, Using IR and Red or IR and Violet images Options

[edstrick]

The currently posted Spirit Pancam panoramas being taken at Larry's Lookout so far have only L1 (infrared) and L5 (red) filter bands (plus R2 and R7). If band L7 (violet-UV) have been taken, they apparently have not been downlinked yet.

With only 2 spectral channels, it's impossible to get true-color images, but cosmetically acceptible images can be generated by averaging the long wavelength band (L2) and the short wavelength band (L5, in this case) as a "pseudo-middle-wavelength" band. Then generate a color image using L1, Average, L5 as Red, Green, Blue bands, respectively.

In Photoshop 4.0 (menus will vary with other editions and you can't do it with Photoshop-Eviscerated .... I mean Photoshop-Elements.... a shorthand for the image processing/generation sequence is as follows. Note: I'll shorten the input image names to "L2"and "L5", and leave out all the more or less obvious "OK" responses and the like.

File > Open > "L2"
File > Open > "L5"

Window > Tile
Image > Mode > Grayscale
(select/click on the other image)
Image > Mode >Grayscale
(JPL's raw jpgs are RGB, even though there is no color data)

Image > Calculations
Source 1 > "L2"
Source 2 > "L5"
Blending > Normal"
Opacity > 50%
Result > NEW

Image > Mode > Grayscale

Window > Show > Channels (if that tool isn't already onscreen)
">" (click on the right-arrow to get the channel menu)
Merge Channels
RGB Color

Red: "L2"
Green: "Untitled-1"
Blue: "L5"

File > Save
For the filename, I pick the shortwavelength file's name, and append the filter numbers: band2filename_25.jpg

I'll often Image > Adjust >Levels or Image > Adjust > Curves to get better brightness distributions, run Filter > Sharpen > Sharpen to crisp up the image, and, and on screwball filter combinations like these, I may boost color saturation
with Image > Adjust > Hue/Saturation before saving the file.

Attached thumbnail(s)