Hyper Image intensity level
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Hi,
How can I find The total number of possible intensity levels in 3D hyper image?
is it the total number of bands? or the sum of the wavelength values ? I'm not sure
I'm calculating the threshold Otsu for hyper image.
Many thanx,
采纳的回答
Iain
2013-6-25
You need to know the bit depth of each "slice" of your hypercube. (We can't tell you this, but its normally 8 bit for a standard RGB image, but can be as high as 24 or as low as 4, for whatever it is that you're looking at.)
Once you know that:
total_number_of_colours = 2^depth_slice_1 * 2^depth_slice_2 * 2^depth_slice_3 ...
Intensity is a little bit different,
Basic_max_intensity = (2^depth_slice_1 - 1) + (2^depth_slice_2 - 1) + (2^depth_slice_3 - 1) ...
Optical_max = (2^depth_slice_1 - 1)*scale_1 + (2^depth_slice_2 - 1) *scale_2 + (2^depth_slice_3 - 1) * scale_3 ... % Where "scale" is a conversion from pixel values to an optical power or energy.
7 个评论
Mona
2013-6-25
Iain
2013-6-25
To "know", you'll need to review the documentation for the bsq file, or the hardware that produced it.
To "have a good guess", if you find the maximum value in each slice, take the log base 2 of that value, and round up (probably to the nearest even number), that'll give you some indication. I would also check that the smallest difference between pixel levels is 1 - if its 2, 4, 8 etc., you may need to divide the max by that number.
Mona
2013-6-25
Mona
2013-6-25
Iain
2013-6-25
The maximum intensity you can store in a 16 bit integer, is indeed 65535.
The maximum intensity you can store in a 8 bit integer is 255.
It is not convenient to store 10, 12 or 14 bit integers in anything other than 16 bit, so it could be that your intensity is 1023, 4095, 16383 of 65535.
Mona
2013-6-25
Iain
2013-6-25
Q1)-Aha so 65536 is the total number of possible intensity levels in 16 bit image?
65536 is the total number of possible values a 16 bit integer can take. Your image is stored in 16 bit integers. This does NOT mean that all 65536 are used by your image format and that there isn't something else to look at in your image format. - You need to check the documentation of the file format you have been given to know the possible intensity levels in your files.
Q2)-Do you know how to get the average of the intensities of all pixels in the hyper image?
average = mean(HyperImage(:));
Will take the average of every 16 bit element in HyperImage
更多回答（2 个）
Walter Roberson
2013-6-25
0 个投票
Each portion of information will have a number of possible states. Multiply together the number of states per portion.
For example, if band #1 had 5 possible values, and band #2 had 32 possible values, then the total number of intensity levels would be (5 x 32) = 160.
When a particular portion is defined as being a certain number of bits, and all of the variations are allowed, then the number of states for that portion is 2 to the power of the number of bits. I could, for example, have defined band #2 as having 5 bits, 2^5 = 32
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