How to get an image when having indices of pixels

Asked Oct 21 '15 at 14:40

Active Oct 21 '15 at 14:40

Viewed 33 times

I am doing a perspective projection of a list of voxel V={v1,v2,v3,...,vn} using the perspective projection matrix 3*4 to get the indices of each pixel pi=(xi,yi).

pi=P*vi

Once I get the indices, I used ReplacePixelValue[] function to get an image but i get an inverted image.

ReplacePixelValue[Image[Table[0, {x, 1, 512}, {y, 1, 680}]], indices -> 1]

I think the problem is come from the coordinates system. So, may be I have to convert the indices to fit the right coordinate system of indices. an I think this function can do the work (note the image dimension is 680*512 in my case)

convert[{x_, y_}] := {x, 512 - y}

Is it Right?

asked Oct 21 '15 at 14:40

BetterEnglish

2,026
13
19

Related http://mathematica.stackexchange.com/a/32377/193 – Dr. belisarius Oct 21 '15 at 14:43
The pitfall post relevant to this question is this one – m_goldberg Oct 21 '15 at 14:58
@belisariusisforth. Indeed, but since you didn't mention what your link was to, I didn't make the connection until you called my attention to it. – m_goldberg Oct 21 '15 at 15:08
@belisariusisforth, I think it is not duplicated because in these link there is any use or explanation of ReplacePixelValue[]. I am surprising why the ReplacePixelValue[] function is done so that it processes the image as a graphic! So, we have to invert the coordinate system each time we have indices not coordinates! – BetterEnglish Oct 21 '15 at 15:10
@Developer2000 Check ReplaceImageValue[ ] – Dr. belisarius Oct 21 '15 at 16:27

How to get an image when having indices of pixels

0 Answers0