"""
JPEG quality settings equivalent to the Photoshop settings.
Can be used when saving JPEG files.
The following presets are available by default:
``web_low``, ``web_medium``, ``web_high``, ``web_very_high``, ``web_maximum``,
``low``, ``medium``, ``high``, ``maximum``.
More presets can be added to the :py:data:`presets` dict if needed.
To apply the preset, specify::
quality="preset_name"
To apply only the quantization table::
qtables="preset_name"
To apply only the subsampling setting::
subsampling="preset_name"
Example::
im.save("image_name.jpg", quality="web_high")
Subsampling
-----------
Subsampling is the practice of encoding images by implementing less resolution
for chroma information than for luma information.
(ref.: https://en.wikipedia.org/wiki/Chroma_subsampling)
Possible subsampling values are 0, 1 and 2 that correspond to 4:4:4, 4:2:2 and
4:2:0.
You can get the subsampling of a JPEG with the
:func:`.JpegImagePlugin.get_sampling` function.
In JPEG compressed data a JPEG marker is used instead of an EXIF tag.
(ref.: https://www.exiv2.org/tags.html)
Quantization tables
-------------------
They are values use by the DCT (Discrete cosine transform) to remove
*unnecessary* information from the image (the lossy part of the compression).
(ref.: https://en.wikipedia.org/wiki/Quantization_matrix#Quantization_matrices,
https://en.wikipedia.org/wiki/JPEG#Quantization)
You can get the quantization tables of a JPEG with::
im.quantization
This will return a dict with a number of arrays. You can pass this dict
directly as the qtables argument when saving a JPEG.
The tables format between im.quantization and quantization in presets differ in
3 ways:
1. The base container of the preset is a list with sublists instead of dict.
dict[0] -> list[0], dict[1] -> list[1], ...
2. Each table in a preset is a list instead of an array.
3. The zigzag order is remove in the preset (needed by libjpeg >= 6a).
You can convert the dict format to the preset format with the
:func:`.JpegImagePlugin.convert_dict_qtables()` function.
Libjpeg ref.:
https://web.archive.org/web/20120328125543/http://www.jpegcameras.com/libjpeg/libjpeg-3.html
"""
# fmt: off
presets = {
'web_low': {'subsampling': 2, # "4:2:0"
'quantization': [
[20, 16, 25, 39, 50, 46, 62, 68,
16, 18, 23, 38, 38, 53, 65, 68,
25, 23, 31, 38, 53, 65, 68, 68,
39, 38, 38, 53, 65, 68, 68, 68,
50, 38, 53, 65, 68, 68, 68, 68,
46, 53, 65, 68, 68, 68, 68, 68,
62, 65, 68, 68, 68, 68, 68, 68,
68, 68, 68, 68, 68, 68, 68, 68],
[21, 25, 32, 38, 54, 68, 68, 68,
25, 28, 24, 38, 54, 68, 68, 68,
32, 24, 32, 43, 66, 68, 68, 68,
38, 38, 43, 53, 68, 68, 68, 68,
54, 54, 66, 68, 68, 68, 68, 68,
68, 68, 68, 68, 68, 68, 68, 68,
68, 68, 68, 68, 68, 68, 68, 68,
68, 68, 68, 68, 68, 68, 68, 68]
]},
'web_medium': {'subsampling': 2, # "4:2:0"
'quantization': [
[16, 11, 11, 16, 23, 27, 31, 30,
11, 12, 12, 15, 20, 23, 23, 30,
11, 12, 13, 16, 23, 26, 35, 47,
16, 15, 16, 23, 26, 37, 47, 64,
23, 20, 23, 26, 39, 51, 64, 64,
27, 23, 26, 37, 51, 64, 64, 64,
31, 23, 35, 47, 64, 64, 64, 64,
30, 30, 47, 64, 64, 64, 64, 64],
[17, 15, 17, 21, 20, 26, 38, 48,
15, 19, 18, 17, 20, 26, 35, 43,
17, 18, 20, 22, 26, 30, 46, 53,
21, 17, 22, 28, 30, 39, 53, 64,
20, 20, 26, 30, 39, 48, 64, 64,
26, 26, 30, 39, 48, 63, 64, 64,
38, 35, 46, 53, 64, 64, 64, 64,
48, 43, 53, 64, 64, 64, 64, 64]
]},
'web_high': {'subsampling': 0, # "4:4:4"
'quantization': [
[6, 4, 4, 6, 9, 11, 12, 16,
4, 5, 5, 6, 8, 10, 12, 12,
4, 5, 5, 6, 10, 12, 14, 19,
6, 6, 6, 11, 12, 15, 19, 28,
9, 8, 10, 12, 16, 20, 27, 31,
11, 10, 12, 15, 20, 27, 31, 31,
12, 12, 14, 19, 27, 31, 31, 31,
16, 12, 19, 28, 31, 31, 31, 31],
[7, 7, 13, 24, 26, 31, 31, 31,
7, 12, 16, 21, 31, 31, 31, 31,
13, 16, 17, 31, 31, 31, 31, 31,
24, 21, 31, 31, 31, 31, 31, 31,
26, 31, 31, 31, 31, 31, 31, 31,
31, 31, 31, 31, 31, 31, 31, 31,
31, 31, 31, 31, 31, 31, 31, 31,
31, 31, 31, 31, 31, 31, 31, 31]
]},
'web_very_high': {'subsampling': 0, # "4:4:4"
'quantization': [
[2, 2, 2, 2, 3, 4, 5, 6,
2, 2, 2, 2, 3, 4, 5, 6,
2, 2, 2, 2, 4, 5, 7, 9,
2, 2, 2, 4, 5, 7, 9, 12,
3, 3, 4, 5, 8, 10, 12, 12,
4, 4, 5, 7, 10, 12, 12, 12,
5, 5, 7, 9, 12, 12, 12, 12,
6, 6, 9, 12, 12, 12, 12, 12],
[3, 3, 5, 9, 13, 15, 15, 15,
3, 4, 6, 11, 14, 12, 12, 12,
5, 6, 9, 14, 12, 12, 12, 12,
9, 11, 14, 12, 12, 12, 12, 12,
13, 14, 12, 12, 12, 12, 12, 12,
15, 12, 12, 12, 12, 12, 12, 12,
15, 12, 12, 12, 12, 12, 12, 12,
15, 12, 12, 12, 12, 12, 12, 12]
]},
'web_maximum': {'subsampling': 0, # "4:4:4"
'quantization': [
[1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 2,
1, 1, 1, 1, 1, 1, 2, 2,
1, 1, 1, 1, 1, 2, 2, 3,
1, 1, 1, 1, 2, 2, 3, 3,
1, 1, 1, 2, 2, 3, 3, 3,
1, 1, 2, 2, 3, 3, 3, 3],
[1, 1, 1, 2, 2, 3, 3, 3,
1, 1, 1, 2, 3, 3, 3, 3,
1, 1, 1, 3, 3, 3, 3, 3,
2, 2, 3, 3, 3, 3, 3, 3,
2, 3, 3, 3, 3, 3, 3, 3,
3, 3, 3, 3, 3, 3, 3, 3,
3, 3, 3, 3, 3, 3, 3, 3,
3, 3, 3, 3, 3, 3, 3, 3]
]},
'low': {'subsampling': 2, # "4:2:0"
'quantization': [
[18, 14, 14, 21, 30, 35, 34, 17,
14, 16, 16, 19, 26, 23, 12, 12,
14, 16, 17, 21, 23, 12, 12, 12,
21, 19, 21, 23, 12, 12, 12, 12,
30, 26, 23, 12, 12, 12, 12, 12,
35, 23, 12, 12, 12, 12, 12, 12,
34, 12, 12, 12, 12, 12, 12, 12,
17, 12, 12, 12, 12, 12, 12, 12],
[20, 19, 22, 27, 20, 20, 17, 17,
19, 25, 23, 14, 14, 12, 12, 12,
22, 23, 14, 14, 12, 12, 12, 12,
27, 14, 14, 12, 12, 12, 12, 12,
20, 14, 12, 12, 12, 12, 12, 12,
20, 12, 12, 12, 12, 12, 12, 12,
17, 12, 12, 12, 12, 12, 12, 12,
17, 12, 12, 12, 12, 12, 12, 12]
]},
'medium': {'subsampling': 2, # "4:2:0"
'quantization': [
[12, 8, 8, 12, 17, 21, 24, 17,
8, 9, 9, 11, 15, 19, 12, 12,
8, 9, 10, 12, 19, 12, 12, 12,
12, 11, 12, 21, 12, 12, 12, 12,
17, 15, 19, 12, 12, 12, 12, 12,
21, 19, 12, 12, 12, 12, 12, 12,
24, 12, 12, 12, 12, 12, 12, 12,
17, 12, 12, 12, 12, 12, 12, 12],
[13, 11, 13, 16, 20, 20, 17, 17,
11, 14, 14, 14, 14, 12, 12, 12,
13, 14, 14, 14, 12, 12, 12, 12,
16, 14, 14, 12, 12, 12, 12, 12,
20, 14, 12, 12, 12, 12, 12, 12,
20, 12, 12, 12, 12, 12, 12, 12,
17, 12, 12, 12, 12, 12, 12, 12,
17, 12, 12, 12, 12, 12, 12, 12]
]},
'high': {'subsampling': 0, # "4:4:4"
'quantization': [
[6, 4, 4, 6, 9, 11, 12, 16,
4, 5, 5, 6, 8, 10, 12, 12,
4, 5, 5, 6, 10, 12, 12, 12,
6, 6, 6, 11, 12, 12, 12, 12,
9, 8, 10, 12, 12, 12, 12, 12,
11, 10, 12, 12, 12, 12, 12, 12,
12, 12, 12, 12, 12, 12, 12, 12,
16, 12, 12, 12, 12, 12, 12, 12],
[7, 7, 13, 24, 20, 20, 17, 17,
7, 12, 16, 14, 14, 12, 12, 12,
13, 16, 14, 14, 12, 12, 12, 12,
24, 14, 14, 12, 12, 12, 12, 12,
20, 14, 12, 12, 12, 12, 12, 12,
20, 12, 12, 12, 12, 12, 12, 12,
17, 12, 12, 12, 12, 12, 12, 12,
17, 12, 12, 12, 12, 12, 12, 12]
]},
'maximum': {'subsampling': 0, # "4:4:4"
'quantization': [
[2, 2, 2, 2, 3, 4, 5, 6,
2, 2, 2, 2, 3, 4, 5, 6,
2, 2, 2, 2, 4, 5, 7, 9,
2, 2, 2, 4, 5, 7, 9, 12,
3, 3, 4, 5, 8, 10, 12, 12,
4, 4, 5, 7, 10, 12, 12, 12,
5, 5, 7, 9, 12, 12, 12, 12,
6, 6, 9, 12, 12, 12, 12, 12],
[3, 3, 5, 9, 13, 15, 15, 15,
3, 4, 6, 10, 14, 12, 12, 12,
5, 6, 9, 14, 12, 12, 12, 12,
9, 10, 14, 12, 12, 12, 12, 12,
13, 14, 12, 12, 12, 12, 12, 12,
15, 12, 12, 12, 12, 12, 12, 12,
15, 12, 12, 12, 12, 12, 12, 12,
15, 12, 12, 12, 12, 12, 12, 12]
]},
}
# fmt: on
| Name | Type | Size | Permission | Actions |
|---|---|---|---|---|
| __pycache__ | Folder | 2755 |
|
|
| BdfFontFile.py | File | 2.75 KB | 0644 |
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| BlpImagePlugin.py | File | 14 KB | 0644 |
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| BmpImagePlugin.py | File | 13.92 KB | 0644 |
|
| BufrStubImagePlugin.py | File | 1.48 KB | 0644 |
|
| ContainerIO.py | File | 2.82 KB | 0644 |
|
| CurImagePlugin.py | File | 1.68 KB | 0644 |
|
| DcxImagePlugin.py | File | 2.09 KB | 0644 |
|
| DdsImagePlugin.py | File | 5.34 KB | 0644 |
|
| EpsImagePlugin.py | File | 11.82 KB | 0644 |
|
| ExifTags.py | File | 8.8 KB | 0644 |
|
| FitsStubImagePlugin.py | File | 1.59 KB | 0644 |
|
| FliImagePlugin.py | File | 4.23 KB | 0644 |
|
| FontFile.py | File | 2.7 KB | 0644 |
|
| FpxImagePlugin.py | File | 6.53 KB | 0644 |
|
| FtexImagePlugin.py | File | 3.23 KB | 0644 |
|
| GbrImagePlugin.py | File | 2.73 KB | 0644 |
|
| GdImageFile.py | File | 2.47 KB | 0644 |
|
| GifImagePlugin.py | File | 28.25 KB | 0644 |
|
| GimpGradientFile.py | File | 3.27 KB | 0644 |
|
| GimpPaletteFile.py | File | 1.24 KB | 0644 |
|
| GribStubImagePlugin.py | File | 1.51 KB | 0644 |
|
| Hdf5StubImagePlugin.py | File | 1.48 KB | 0644 |
|
| IcnsImagePlugin.py | File | 11.44 KB | 0644 |
|
| IcoImagePlugin.py | File | 9.94 KB | 0644 |
|
| ImImagePlugin.py | File | 10.53 KB | 0644 |
|
| Image.py | File | 113.4 KB | 0644 |
|
| ImageChops.py | File | 7.13 KB | 0644 |
|
| ImageCms.py | File | 36.22 KB | 0644 |
|
| ImageColor.py | File | 8.44 KB | 0644 |
|
| ImageDraw.py | File | 29.94 KB | 0644 |
|
| ImageDraw2.py | File | 4.9 KB | 0644 |
|
| ImageEnhance.py | File | 3.12 KB | 0644 |
|
| ImageFile.py | File | 20.74 KB | 0644 |
|
| ImageFilter.py | File | 15.46 KB | 0644 |
|
| ImageFont.py | File | 43.49 KB | 0644 |
|
| ImageGrab.py | File | 3.54 KB | 0644 |
|
| ImageMath.py | File | 6.88 KB | 0644 |
|
| ImageMode.py | File | 1.6 KB | 0644 |
|
| ImageMorph.py | File | 7.67 KB | 0644 |
|
| ImageOps.py | File | 18.03 KB | 0644 |
|
| ImagePalette.py | File | 6.2 KB | 0644 |
|
| ImagePath.py | File | 336 B | 0644 |
|
| ImageQt.py | File | 5.67 KB | 0644 |
|
| ImageSequence.py | File | 1.81 KB | 0644 |
|
| ImageShow.py | File | 6.15 KB | 0644 |
|
| ImageStat.py | File | 3.81 KB | 0644 |
|
| ImageTk.py | File | 9.11 KB | 0644 |
|
| ImageTransform.py | File | 2.78 KB | 0644 |
|
| ImageWin.py | File | 7.02 KB | 0644 |
|
| ImtImagePlugin.py | File | 2.15 KB | 0644 |
|
| IptcImagePlugin.py | File | 5.6 KB | 0644 |
|
| Jpeg2KImagePlugin.py | File | 8.52 KB | 0644 |
|
| JpegImagePlugin.py | File | 27.16 KB | 0644 |
|
| JpegPresets.py | File | 12.41 KB | 0644 |
|
| McIdasImagePlugin.py | File | 1.71 KB | 0644 |
|
| MicImagePlugin.py | File | 2.54 KB | 0644 |
|
| MpegImagePlugin.py | File | 1.76 KB | 0644 |
|
| MpoImagePlugin.py | File | 4.14 KB | 0644 |
|
| MspImagePlugin.py | File | 5.43 KB | 0644 |
|
| PSDraw.py | File | 6.51 KB | 0644 |
|
| PaletteFile.py | File | 1.08 KB | 0644 |
|
| PalmImagePlugin.py | File | 8.89 KB | 0644 |
|
| PcdImagePlugin.py | File | 1.47 KB | 0644 |
|
| PcfFontFile.py | File | 6.2 KB | 0644 |
|
| PcxImagePlugin.py | File | 5.41 KB | 0644 |
|
| PdfImagePlugin.py | File | 7.49 KB | 0644 |
|
| PdfParser.py | File | 33.58 KB | 0644 |
|
| PixarImagePlugin.py | File | 1.61 KB | 0644 |
|
| PngImagePlugin.py | File | 42.79 KB | 0644 |
|
| PpmImagePlugin.py | File | 4.34 KB | 0644 |
|
| PsdImagePlugin.py | File | 7.56 KB | 0644 |
|
| PyAccess.py | File | 9.37 KB | 0644 |
|
| SgiImagePlugin.py | File | 5.96 KB | 0644 |
|
| SpiderImagePlugin.py | File | 9.31 KB | 0644 |
|
| SunImagePlugin.py | File | 4.2 KB | 0644 |
|
| TarIO.py | File | 1.41 KB | 0644 |
|
| TgaImagePlugin.py | File | 6.18 KB | 0644 |
|
| TiffImagePlugin.py | File | 66.86 KB | 0644 |
|
| TiffTags.py | File | 14.22 KB | 0644 |
|
| WalImageFile.py | File | 5.4 KB | 0644 |
|
| WebPImagePlugin.py | File | 10.54 KB | 0644 |
|
| WmfImagePlugin.py | File | 4.56 KB | 0644 |
|
| XVThumbImagePlugin.py | File | 1.9 KB | 0644 |
|
| XbmImagePlugin.py | File | 2.37 KB | 0644 |
|
| XpmImagePlugin.py | File | 3 KB | 0644 |
|
| __init__.py | File | 3.18 KB | 0644 |
|
| __main__.py | File | 41 B | 0644 |
|
| _binary.py | File | 1.75 KB | 0644 |
|
| _imaging.cpython-36m-x86_64-linux-gnu.so | File | 650.13 KB | 0755 |
|
| _imagingcms.cpython-36m-x86_64-linux-gnu.so | File | 38.05 KB | 0755 |
|
| _imagingft.cpython-36m-x86_64-linux-gnu.so | File | 41.98 KB | 0755 |
|
| _imagingmath.cpython-36m-x86_64-linux-gnu.so | File | 24.43 KB | 0755 |
|
| _imagingmorph.cpython-36m-x86_64-linux-gnu.so | File | 8.12 KB | 0755 |
|
| _imagingtk.cpython-36m-x86_64-linux-gnu.so | File | 9.37 KB | 0755 |
|
| _tkinter_finder.py | File | 224 B | 0644 |
|
| _util.py | File | 359 B | 0644 |
|
| _version.py | File | 50 B | 0644 |
|
| _webp.cpython-36m-x86_64-linux-gnu.so | File | 40.82 KB | 0755 |
|
| features.py | File | 8.8 KB | 0644 |
|