why I use imread fuction this photo not RGB array?

2 次查看（过去 30 天）
Latch Wu
Latch Wu 2023-9-18
编辑： DGM 2023-9-19
temp = imread('image.png');
% temp = 3000x4000 uint8?
why this photo don't have RGB 3D-array?
because I use pixelLabelDatastore function. then show result
Error using matlab.io.datastore.PixelLabelDatastore.label2cat
Pixel label image must have 3 channels when RGB-triplet pixel label IDs are specified.
Error in matlab.io.datastore.PixelLabelDatastore/label2categorical (line 1032)
L = matlab.io.datastore.PixelLabelDatastore.label2cat(...
Error in matlab.io.datastore.PixelLabelDatastore/readimage (line 578)
C = this.label2categorical(C, info);
It let me check the photo, why don't have rgb 3d array?

请先登录，再回答此问题。

采纳的回答

DGM
DGM 2023-9-18
Ran in:
It's an indexed-color image. If you want it to be RGB, you can convert it.
% this is an indexed image and its corresponding color table
[inpict map] = imread('https://www.mathworks.com/matlabcentral/answers/uploaded_files/1485727/image.png');
% convert it to RGB
inpict = ind2rgb(inpict,map);
size(inpict)
ans = 1×3
3000 4000 3
imshow(inpict,'border','tight')
See also:
https://www.mathworks.com/help/matlab/creating_plots/image-types.html
  2 个评论
Latch Wu
Latch Wu 2023-9-18
DGM, thanks your reply,
I has trouble in this code
pxds = pixelLabelDatastore(labelDir,classes,labelIDs);
C = readimage(pxds,1);
when I have many indexed-color image[s] in labelDir.
how to use pixelLabelDatastore function,
whether every indexed-color image file that must be transfer to RGB struction, then run function "pixelLabelDatastore" ?
DGM
DGM 2023-9-19
编辑：DGM 2023-9-19
Ran in:
I don't have CVT, so I'm not familiar with pixelLabelDatastore, but I think the way labelIDs are specified depends on the type of each image.
If it's an RGB image, they're specified as a color table, but if the file is indexed color, the labels are specified as the index.
% do it with an RGB input
classes = {'a','b','c','d','e','f'};
labelIDs = [0 0 0; 102 102 156; 128 64 128; 107 142 35; 0 0 142; 70 70 70];
pxds = pixelLabelDatastore('./',classes,labelIDs);
A = readimage(pxds,2);
size(A)
ans = 1×2
3000 4000
unique(A)
ans = 6×1 categorical array
a b c d e f
% do it with an indexed input
classes = {'a','b','c','d','e','f'};
labelIDs = 0:5;
pxds = pixelLabelDatastore('./',classes,labelIDs);
A = readimage(pxds,1);
size(A)
ans = 1×2
3000 4000
unique(A)
ans = 6×1 categorical array
a b c d e f
If the image type or classes vary within a directory, I see no way to handle that.

请先登录，再进行评论。

更多回答（0 个）

类别

在 Help Center 和 File Exchange 中查找有关 Display Image 的更多信息

标签

产品

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by