XnView Software

-oX- wrote: Wed Jun 26, 2019 8:24 pm another way is to support the WIC (Windows Image Component)
if the AVIF-Extension is installed (Windows Store) all Programs use WIC automatically support AVIF

xnview wrote: Mon Mar 23, 2020 10:17 am

• Quantizer for color -->
Quantization of color

• Quantizer for alpha -->
Quantization of alpha channel

I use the term of AVIF library

AvifColorLossless AvifColorMin AvifColorMax
AvifAlphaLossless AvifAlphaMin AvifAlphaMax

cbColorLossless sbColorMin sbColorMax
cbAlphaLossless sbAlphaMin sbAlphaMax

https://joedrago.github.io/colorist/docs/Usage.html wrote:

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-q, –quality

Choose a lossy quality (0-100) for any output file format that supports it (JPG, JP2 if not using -2, WebP). The lower the value, the lower the file size and quality. For WebP and JP2 (without -2), 100 is lossless.

See --quantizer for an explanation of how quality is mapped to AVIF encoding.

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–quantizer MIN,MAX

Quantizer Ranges: 0-63

The quality emitted by AVIF encoder is controlled by two quantizer values (a minimum and maximum). The higher these numbers are, the worse the image quality will be. For example, choosing [0,0] will create a lossless AVIF, and choosing [63,63] will encode something that barely looks like the original image.

If this option isn't used, colorist will map the single -q quality value to these, by slowly ramping up the maximum quantizer first as you turn down the quality from 100, until it caps out at 63 (e.g. Q=99 will have a max quantizer of 1). The min quantizer will begin to ramp up from 0 in the 60s until it hits 63 right at Q=1, making Q=1 have quantizer settings of [63,63].

Due to how the encoder uses these values, there can be a bit of a plateau in the Q30-Q50 range, but dual ramp provides a reasonable single dial for quality. Q100->Q60 has a reasonable descent in quality, and Q30->Q1 really trashes the image.

Use this option if you want to specify your own min/max quantizers instead.

https://github.com/link-u/cavif wrote:

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        q           Constant Quality
        cq          Constrained Quality
        --bit-rate  Bit rate of output image.
        --crf       CQ Level in CQ rate control mode
        --qmin      Minimum (Best Quality) Quantizer
        --qmax      Maximum (Worst Quality) Quantizer
        --adaptive-quantization
                    Set adaptive-quantization mode

https://github.com/AOMediaCodec/libavif/blob/master/apps/avifenc.c wrote:

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    printf("    --min Q                           : Set min quantizer for color (%d-%d, where %d is lossless)\n",
           AVIF_QUANTIZER_BEST_QUALITY,
           AVIF_QUANTIZER_WORST_QUALITY,
           AVIF_QUANTIZER_LOSSLESS);
    printf("    --max Q                           : Set max quantizer for color (%d-%d, where %d is lossless)\n",
           AVIF_QUANTIZER_BEST_QUALITY,
           AVIF_QUANTIZER_WORST_QUALITY,
           AVIF_QUANTIZER_LOSSLESS);
    printf("    --minalpha Q                      : Set min quantizer for alpha (%d-%d, where %d is lossless)\n",
           AVIF_QUANTIZER_BEST_QUALITY,
           AVIF_QUANTIZER_WORST_QUALITY,
           AVIF_QUANTIZER_LOSSLESS);
    printf("    --maxalpha Q                      : Set max quantizer for alpha (%d-%d, where %d is lossless)\n",
           AVIF_QUANTIZER_BEST_QUALITY,
           AVIF_QUANTIZER_WORST_QUALITY,
           AVIF_QUANTIZER_LOSSLESS);

• patent free AVIF image format (AV1 key frame)
• AVIF Support

oakside wrote: Wed Sep 28, 2022 3:54 pm Will AVIF get a "quality" setting [...]? Currently, there is no easy way to set quality (1-100, like others).