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Image
Image.JPEG
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Method Image.JPEG.decode_header()
- Method
decode_header
object decode(string data)
object decode(string data, mapping options)
mapping _decode(string data)
mapping _decode(string data, mapping options)
mapping decode_header(string data) - Description
Decodes a JPEG image. The simple decode function
simply gives the image object, the other functions gives
a mapping of information (see below).
The options argument may be a mapping
containing zero or more decoding options:
| "block_smoothing" : int(0..1) | Do interblock smoothing. Default is on (1).
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| "fancy_upsampling" : int(0..1) | Do fancy upsampling of chroma components.
Default is on (1).
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| "method" : int | DCT method to use. Any of
IFAST , ISLOW , FLOAT , DEFAULT or FASTEST .
DEFAULT and FASTEST is from the jpeg library,
probably ISLOW and IFAST respective.
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| "scale_num" : int(1..) | Rescale the image when read from JPEG data.
My (Mirar) version (6a) of jpeglib can only handle
1/1, 1/2, 1/4 and 1/8.
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| "scale_denom" : int(1..) |
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_decode and decode_header gives
a mapping as result, with this content:
| "comment" : string | Comment marker of JPEG file, if present.
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| "xsize" : int | Size of image
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| "ysize" : int |
| "xdpi" : float | Image dpi, if known.
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| "ydpi" : float |
| "type" : string | File type information as MIME type. Always "image/jpeg".
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| "num_compontents" : int | Number of channels in JPEG image.
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| "color_space" : string | Color space of JPEG image. Any of "GRAYSCALE", "RGB", "YUV",
"CMYK", "YCCK" or "UNKNOWN".
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| "density_unit" : int(0..2) | The unit used for x_density and y_density.
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| "x_density" : int | Density of image.
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| "y_density" : int |
| "adobe_marker" : int(0..1) | If the file has an Adobe marker.
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| "quant_tables" : mapping(int:array(array(int))) | JPEG quant tables.
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| "quality" : int(0..100) | JPEG quality guess.
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Image.JPEG.decode()