How do I get a colormap from JPEG file?
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Julián Francisco
am 24 Okt. 2011
Kommentiert: Walter Roberson
am 7 Jun. 2016
Hi. I have a jpg image file of the surface of Neptune. My intention is to build a texture mapping ( see Matlab's help about this topic ). I have used the command imread with the file but jpg files have not a colormap (in general, the command imread produces an MxNx3 matriz and a colormap is a Mx3 matrix). I would like to know how I could do it.
Like a image is more valuable than 1000 words (sometimes), my purpose is doing something like that (see example) but for Neptune.
2 Kommentare
Image Analyst
am 24 Okt. 2011
The jpg image is a true color image. What do you mean by a topographic image? You mean like a geological survey topographic map with contour lines on it and you want that somehow transferred to the surface of a spherical object? What proportion of the sphere should this 2D rectangle cover? A tiny spot? A whole hemisphere? Something in between? Or do you want some kind of 2.5D terrain image with mountains and things sticking above the surface of the sphere?
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Walter Roberson
am 24 Okt. 2011
You can use the two-output form of rgb2ind() to extract a colormap from a true-color image.
I am not certain how you plan to map colormap indices to altitudes, though.
Weitere Antworten (2)
user4552
am 7 Jun. 2016
how can you convert 2D image to 3D image, knowing that the first image is color image but 2D?
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Walter Roberson
am 7 Jun. 2016
permute(YourRGBIMage, [1 2 4 3])
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