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I'm working on image processing, and I have an image that has been DCT'd and quantized for 8 x 8 blocks of the 512 x 512 matrix, now I have to find how many quantizing levels that the image has. Do I need to take the top left pixel and place it in to an array and then place this on a graph calling hist?

Matthew Simoneau
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Stina
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1 Answers1

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length(unique(x(:))), where x is your image array. This is appropriate for grayscale images.

Oliver Charlesworth
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  • Is x the 512 x 512 full image or an 8 x 8 block contained in it? Thank you – Stina Feb 23 '11 at 15:50
  • @Stina: It's whatever you want it to be! Your original question isn't very clear; are you trying to get the *overall* number of levels for the *overall* image, or something else? – Oliver Charlesworth Feb 23 '11 at 15:57
  • I appreciate I'm asking about an assignment but it is a subpart and the question is: "Estimate the required number of quantization levels for DCT coecients for different values of the quality factor". I think my vagueness in my question stems from the fact that I am unsure of what I am being asked – Stina Feb 23 '11 at 16:04