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# Tag Info

## Hot answers tagged image-compression

15 votes
Accepted

• 28.3k
3 votes

### Are the FFT coefficients symmetric in image processing?

Your observation is basically right. Given a 2D discrete-space real sequence $x[n_1,n_2]$, its 2D discrete-space Fourier transform $X(e^{j{\omega}_1},e^{j{\omega}_2})$ is a complex valued function ...
• 28.3k
3 votes
Accepted

### How does Jpeg encoding affect the final file size of 24BPP RGB and 8BPP grayscale image?

Take a standard R-G-B coded 24-bit image. First, suppose that all channels are coded independently. If by chance, R, G, and B are equal, each one will be converted to the same JPEG file with size $s$. ...
• 31.9k
3 votes

### Random Noise Removal In Images

There are a lot of ways to do image denoising. I will give several known examples: Hard/soft thrsholding of the wavelet decomposition: Do a wavelet decomposition of the image and for zero all ...
3 votes
Accepted

• 31.9k
2 votes

### How does a wavelet help in image compression?

I think that modern video codecs using block transforms in intra mode have better subjective/objective compression or at least on par with jpeg 2000. See eg: https://hal.archives-ouvertes.fr/hal-...
• 3,434
2 votes
Accepted

### The magnitude of taking discrete cosine transform of an image two times is similar to the original

It's beacuse the inverse discrete fourier transform (DCT) is almost identical to the forward DCT. So taking twice the transform will be similar to the original signal. In fact if you provide which DCT ...
• 28.3k
2 votes

### JPEG DCT padding

What if image dimension not a multiple of 8?How padding works? If the image width and height are not multiple of 8, the image will be padded with zeroes most commonly.. How 8*8 blocks are chosen ...

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