jpegqs(1) · carta

Usage

jpegqs [options] input.jpg output.jpg

Overview

This program tries to recover the lost precision of DCT coefficients based on a quantization table from a JPEG image. The result is saved as a JPEG image with quantization set to 1 (like a JPEG saved at 100% quality).

Options

-q, --quality n: Quality setting (0-6, default is 3)/home/rainbow/Desktop/pngtest/jpegrestore/jpegqs.1

-n, --niter n: Number of iterations (default is 3)

: * More iterations can make the result look like CG art, can make the photos look unnatural.

-t, --threads n: Set the number of CPU threads to use

-o, --optimize: Option for libjpeg to produce smaller output file

-v, --verbose n: Print libjpeg debug output

-i, --info n: Print quantsmooth debug output (default is 15).

Use the sum of flags:

0 - silent

1/2/4 - various information

8 - processing time

16 - SIMD type

* The processing time includes only the smoothing algorithm, jpeg reading and writing time is not included.

-p, --cpu n: Use to lower the SIMD type if CPU detection fails:

0 - auto

1 - scalar

2 - SSE2

3 - AVX2

4 - AVX512

* x86 build selects between modes 1-3, x86_64 from 2-4

Quality

The quality setting sets a combination of flags for processing:

3. default

4. adds DIAGONALS flag: smoother diagonal edges, ~1.5 times slower

5. adds JOINT_YUV flag: chroma channels will depend from luminance, better color consistency

6. adds UPSAMPLE_UV flag: non-blurring chroma upsampling, unlike fancy upsampling from libjpeg

levels 0-2 is the same as 4-6, but with LOW_QUALITY flag

~10 times faster, but the quality is lower

LOW_QUALITY implies DIAGONALS (always set)

Project page

https://github.com/ilyakurdyukov/jpeg-quantsmooth