Signal Processing Stack Exchange
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Questions tagged [image-compression]

image compression is a process of representing an image file or datastream using fewer bytes. compression can be "lossless", in which the original data can be recovered exactly, or it can be "lossy", in which some detail is lost for the sake of better compression.

image compression is a process of representing an image file or datastream using fewer bytes. compression can be "lossless", in which the original data can be recovered exactly, or it can be "lossy", in which some detail is lost for the sake of better compression.

Examples of "lossy" compression are JPEG, which attempts to quantize the data in a manner that preserves image appearance and GIF, in which the number of colors is reduced to 256 or fewer. PNG is an example of lossless image compression, at least to the extent that up to 16 bits of data per color sample are preserved.

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What are some good images to use when comparing image compression algorithms?

There was a question about images that are hard to compress. Are there images that are better suited to testing compression quality than others? Maybe an image of diagonal lines of specific colors at a specific angle would be more likely to show…
gman
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Why choose anything but highest compression for PNG?

I just installed LibreOffice for the first time. In the Impress application for presentation slides, when I choose to save an image on a slide, the file type is PNG and there is a slider for compression, positioned approximately midway at 6.…
user2153235
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Loss in converting YUV to PNG

I have a YUV 420NV12 image. I'm using ffmpeg to convert the YUV file to PNG and then back again to YUV. ffmpeg -s 640x480 -pix_fmt nv12 -i testold.yuv test-640x480 test.png ffmpeg -i test.png -s 640x480 -pix_fmt nv12 testnew.yuv When I compare the…
Navin Prashath
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Why don't DSLR cameras default to png instead of jpeg?

I'm working with a new DSLR camera for a Computer Vision application and I noticed most of them default to saving in the lossy JPEG format. Initially, this caused some problems in my application and I started working with the RAW format, and saved…
dev_nut
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Does image size impact compression efficiency differently in different formats?

E.g., if an image is, say, 600px x 400px and the PNG format produces a smaller file size than JPG, does this hold true at any image size? If the image were 600,000px x 400,000px would the two file sizes still have the same relative proportions? Or…
dev_willis
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Compression algorithm to compress image relative to similar image

Is there an algorithm which can take advantage of a previous image in order to compress the next image with a level of compression / quality than otherwise? I have an app which takes a photo of the sky ever few minutes and then uploads that to a…
James S
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Reconstructing image from the dwt coefficients

I am trying to compress and reconstruct an image but facing problems with the data type of the compressed image pixel values which are of float64 and therefore, when I am trying to retrieve the pixel values from the compressed image , reconstruction…
Arpit Jadon
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