Mercurial > octave
changeset 24613:93219261164d
rgb2gray: fix conversion of nd images
* scripts/image/rgb2gray.m: do not squeeze the 3rd dimension when
converting a nd image to grayscale. Fix tests for ND input. Also,
use existing private function to perform the reshape back to the
original shape. Remove comment about patch #8709 which only applies
to the ntsc conversion related functions.
| author | Carnë Draug <carandraug@octave.org> |
|---|---|
| date | Wed, 17 Jan 2018 17:55:46 +0000 |
| parents | 6c8822790411 |
| children | 3daa67b7a243 |
| files | scripts/image/rgb2gray.m |
| diffstat | 1 files changed, 8 insertions(+), 18 deletions(-) [+] |
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--- a/scripts/image/rgb2gray.m Wed Jan 17 09:30:14 2018 -0800 +++ b/scripts/image/rgb2gray.m Wed Jan 17 17:55:46 2018 +0000 @@ -21,12 +21,12 @@ ## @deftypefnx {} {@var{gray_map} =} rgb2gray (@var{rgb_map}) ## Transform an image or colormap from red-green-blue (RGB) color space to ## a grayscale intensity image. -## +## ## The input may be of class uint8, int8, uint16, int16, single, or double. ## The output is of the same class as the input. ## ## Implementation Note: -## The grayscale intensity is calculated as +## The grayscale intensity is calculated as ## ## @example ## @group @@ -56,30 +56,20 @@ ## Reference matrix for transform from http://en.wikipedia.org/wiki/YIQ. ## Matlab uses this matrix for their conversion with oddly more precision. xform = [0.298936; 0.587043; 0.114021]; - - ## Note that if the input is of class single, we also return an image - ## of class single. This is Matlab incompatible by design, since - ## Matlab always returning class double, is a Matlab bug (see patch #8709) I = rgb * xform; - ## Restore size if necessary - if (is_im) - if (is_nd) - I = reshape (I, [sz(1), sz(2), sz(4)]); - else - I = reshape (I, sz(1:2)); - endif - endif + sz(3) = 1; # grayscale images have 3rd dimension of length 1 + I = colorspace_conversion_revert (I, sz, is_im, is_nd); ## Restore integer class if necessary if (is_int) if (cls(end) == "8") # uint8 or int8 - I *= 255; + I *= 255; if (cls(1) == "i") # int8 I -= 128; endif else # uint16 or int16 - I *= 65535; + I *= 65535; if (cls(1) == "i") # int16 I -= 32768; endif @@ -101,9 +91,9 @@ ## Test ND input %!test %! rgb = rand (16, 16, 3, 5); -%! I = zeros (16, 16, 5); +%! I = zeros (16, 16, 1, 5); %! for i = 1:5 -%! I(:,:,i) = rgb2gray (rgb(:,:,:,i)); +%! I(:,:,1,i) = rgb2gray (rgb(:,:,:,i)); %! endfor %! assert (rgb2gray (rgb), I);