The memory size occupied by an image

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K. Taieb
K. Taieb 2020-6-19
编辑： K. Taieb 2020-6-23
I did not understand why when I save a 2D matrix (200 * 200) in an image (imwrite), the memory size occupied by this image is less than the memory occupied by the image created by a matrix (1 * 25000). the number of elements in the first case is greater than in the second.
do you have any explanation?
Thank you

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回答（1 个）

Steven Lord
Steven Lord 2020-6-19
Compression, perhaps.
Let me generate a random matrix. What's the most compact way you can think of to write a command to regenerate it? [I'm not going to give you the command I used to generate it.]
A =
1 8 8 -6 -6
3 7 -5 -7 8
0 10 -10 -9 -6
9 -10 5 5 -9
5 -8 1 10 -6
Here's a second matrix, same size. Can you write a shorter command to generate B than you could to generate A?
B =
0 0 0 0 0
0 0 0 0 0
0 0 0 0 0
0 0 0 0 0
0 0 0 0 0
Even if I gave you the full command to create A, it would still be longer than the command I used to generate B.
  1 个评论
K. Taieb
K. Taieb 2020-6-19
编辑：K. Taieb 2020-6-23
Thank you!
In my case, the matrixes are of type uint16 like B in your example.
I will show you an example:
I have a matrix A with 40000 elements and B with 25000 elements.
A=200*ones(200,200);
B=200*ones(25000,1);
imwrite(A,['image' num2str(1) '.jp2']);
imwrite(B,['image' num2str(2) '.jp2']);
The size of memory :
for B: image 1 = 240 byte.
for A: image 2 = 4,11 kilobyte.
I thought that the memory size occupied by the image 1 is more important because the nomber of elements of A is more then in B.

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