how to convert a cell array into an image?
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I fetched an image from sql database but its returning format is like i=[75839 int8] how can i convert it into image plz help me out
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Guillaume
2014-10-5
If the bytes you get are truly a jpg image, you may be able to decode it with java:
jimage = javax.imageio.ImageIO.read(java.io.ByteArrayInputStream(d));
height = jimage.getHeight;
width = jimage.getWidth;
pixels = reshape(typecast(jimage.getData.getDataStorage, 'uint8'), [3,width,height]);
img = cat(3, ...
transpose(reshape(pixels(3,:,:), [width,height])), ...
transpose(reshape(pixels(2,:,:), [width,height])), ...
transpose(reshape(pixels(1,:,:), [width,height])));
12 个评论
kanwal
2014-10-5
Yes, I missed the fact that the data came as int8. I automatically assumed it was uint8 as int8 doesn't make much sense. I don't know if you can fetch the data directly as uint8, but if you can't, just change the first line to:
jimage = javax.imageio.ImageIO.read(java.io.ByteArrayInputStream(typecast(d, 'uint8')));
kanwal
2014-10-6
Guillaume
2014-10-6
I assume that jimage is empty then. For some reason, the image decoding failed without raising an exception.
Can you save your d in a mat file and attach that so I can have a look. The fragment you've posted is the valid beginning of a png image but possibly there's something wrong later on.
Another option would be to save your d as a binary file (with fopen / fwrite / fclose) and then read it back with imread.
kanwal
2014-10-6
This is not the same d as you posted earlier, but no matter, the code I gave you works regardless of the type of the image (as long as it's recognised by java, png and jpeg are ok).
In any case, I had no issue seeing your image with the code I've posted. This is exacty what I typed:
d=d{1};
jimage = javax.imageio.ImageIO.read(java.io.ByteArrayInputStream(typecast(d, 'uint8')));
height = jimage.getHeight;
width = jimage.getWidth;
pixels = reshape(typecast(jimage.getData.getDataStorage, 'uint8'), [3,width,height]);
img = cat(3, ...
transpose(reshape(pixels(3,:,:), [width,height])), ...
transpose(reshape(pixels(2,:,:), [width,height])), ...
transpose(reshape(pixels(1,:,:), [width,height])));
imshow(img)
kanwal
2014-10-6
Guillaume
2014-10-6
On which line do you get this error?
As I said, after importing the d.mat you posted into matlab, just running the code above works and displays the image of a yellow packet with 'Bonus tristar' written on it.
kanwal
2014-10-7
jumana eltrabelsi
2022-4-14
Thank you allot, Its work for me too
更多回答（1 个）
Image Analyst
2014-10-4
编辑：Image Analyst
2014-10-4
You need to take the (badly-named) i and reshape it into a 2 or 3D array, but you need to know the number of rows and columns.
cellContents = cell2mat(i); % Convert from cell to double.
grayImage = reshape(cellContents, [rows, columns]);
imshow(grayImage, []);
8 个评论
kanwal
2014-10-5
kanwal
2014-10-5
AS IA said, you will have to reshape that d into a 2D image, so you need to know the height and width of the image.
Now since, 75389 is a prime number, there's no way that it can be reshaped into a rectangle, so most likely, there is a header to the image. Do you know what that header is (or what the format of the image is)? If not, can you post the first few value of d (for example d(1:40))?
kanwal
2014-10-5
Guillaume
2014-10-5
Can you show the first few bytes d?
d(1:40)
kanwal
2014-10-5
Guillaume
2014-10-5
Your image is a png image, not a jpeg. The code I posted in my answer, with the typecast fix, should decode it.
kanwal
2014-10-6
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