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Questions tagged [lossy-compression]

36 questions
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fl_lossy progressive in image's URL?

I've seen a few websites are having images with a quite strange path, like https://..../image/upload/fl_lossy.progressive,q_65,f_auto/c_fill,w_180,h_180/....webp Was this path generated by a specific/standart software? Does this URL path have a…
Shirker
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Ways to compress GIFs in Swift?

My gif generator function reduces the resolution and minimizes the frames from a series of photos, but I don't have anything to reduce the amount of colors or make it lossy. How would I go about doing this in Swift 4? func generateGif(photos:…
Chewie The Chorkie
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How to compress subpixel text bitmap

Recently, I am doing jobs about Windows clearType text compression; Windows text font use sub-pixel rendering tech which making the text font edge full of mess colors, like below. I have try the jpeg, zstd, lz4, the compression ratio of them cannot…
haie1011
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PageSpeed Insights optimize .jpg with jpegoptim lossy ideal %?

I am trying to remove 'Optimize images' warning from Google PageSpeed Insights. Validator says I can do about 40 - 50% image reduction for each jpg on my website. So I installed jpegoptim on Ubuntu and firstly try lossless optimization. It did about…
Anubix
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Could a compression algorithm be lossless and lossy at the same time?

I have seen ffmpeg has some codecs (e.g. H.264) which are defined as lossless and lossy at the same time, and from my understanding, lossless and lossy are mutually exclusive: a compression algorithm either losses information or doesn't. How is it…
Pasta Fresca
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OpenCV setting certain pixels to a color creates shades of the color

as you can see in the code, I have a completely white image. Then I assign the color green to certain pixels, while iterating over the image. However, in the result image, there are pixels with shades of green and not just one green color. This is…
Nick
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Compute the CR for lightweight temporal compression

I am working on the LTC algorithm to compress the data int SIZE =256; int data[SIZE ]={700,...}; // input dataset (original data) After executed the LTC I get on output (compressed data) like this: //format: "number:count" --> e.g.,…
lena
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Python PIL Rotate (Image Result Quality)

I'm using Python 3.11 with Pillow 9.3.0 and OpenCV 4.6.0.66. I want to make sure if I doing 90 degree rotate with PIL, the quality of image is same. ret = False frame = None camera = cv2.VideoCapture(0, cv2.CAP_DSHOW) if camera.isOpened(): …
jon_17z
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good compression method or library for time-sequence of float matrix (mp4 for int matrix case though)

question Suppose I have a sequence of float matrix, which has strong temporal correlation. How to compress such a float matrix sequence? I think, it could be nice if there is a method which considers both spatial and temporal correlation as in…
orematasaburo
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Converting audio files from .wav to mp3 using GNU Parallel

I am trying to convert a full folder of audio files(.wav) to .mp3 by changing the bitrate. The problem is each audio file name consist of multiple '.' and ends with .wav. I am using gnu-parallel to convert the audio signals bitrate and save them as…
blat_spin
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Lossy Image Compression Metrics

I'm wondering about what types of metrics I can use for comparing different (lossy) image compression methods (i.e., things other than compression ratio). For example, comparing JPEG, JPEG 2000, and JPEG XR on a set of different images. Ideally I'd…
dukedoug
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Determining Lost Image Quality Through Lossy Compression

I recently came upon a question that I haven't seen anywhere else while searching about lossy compression. Can you determine the quality lost through a certain algorithm? I have been asking around and it seems like that there isn't a sure way to…
Ian Zhang
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How to specify how lossy/lossless a .webm conversion will be (in ffmpeg)?

I can't seem to understand how to make the conversion lossless (or at least visually lossless)? The outputs have some fast moving parts at times, and the output would become blocky; I would like to keep it as lossless as possible, while still…
DistantDigit
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List to int lossy conversion

I'm trying to solve a challenge and the function must return a long integer and takes an int and List as parameters but i keep getting the following error: Solution.java:32: error: incompatible types: possible lossy conversion from long to…
d.r.
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How can I use JPEG Compression algorithm for 1D data (e.g. a line)?

I have a (time series) data that looks like {21,21,22,23,24,23,....} and I'm trying to implement the jpeg algorithm in JAVA to see how the jpeg compression works on such 1D data (my plan is to compare all sorts of compression algorithms). I know…
Chuckster
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