Release Notes

Open Source Used In AsyncOS 8.8 for Cisco Web Security Appliances
64
Generates a default scan script for writing a progressive-JPEG file.
This is the recommended method of creating a progressive file,
unless you want to make a custom scan sequence. You must ensure that
the JPEG color space is set correctly before calling this routine.
Compression parameters (cinfo fields) include:
int block_size
Set DCT block size. All N from 1 to 16 are possible.
Default is 8 (baseline format).
Larger values produce higher compression,
smaller values produce higher quality.
An exact DCT stage is possible with 1 or 2.
With the default quality of 75 and default Luminance qtable
the DCT+Quantization stage is lossless for value 1.
Note that values other than 8 require a SmartScale capable decoder,
introduced with IJG JPEG 8. Setting the block_size parameter for
compression works with version 8c and later.
J_DCT_METHOD dct_method
Selects the algorithm used for the DCT step. Choices are:
JDCT_ISLOW: slow but accurate integer algorithm
JDCT_IFAST: faster, less accurate integer method
JDCT_FLOAT: floating-point method
JDCT_DEFAULT: default method (normally JDCT_ISLOW)
JDCT_FASTEST: fastest method (normally JDCT_IFAST)
The FLOAT method is very slightly more accurate than the ISLOW method,
but may give different results on different machines due to varying
roundoff behavior. The integer methods should give the same results
on all machines. On machines with sufficiently fast FP hardware, the
floating-point method may also be the fastest. The IFAST method is
considerably less accurate than the other two; its use is not
recommended if high quality is a concern. JDCT_DEFAULT and
JDCT_FASTEST are macros configurable by each installation.
unsigned int scale_num, scale_denom
Scale the image by the fraction scale_num/scale_denom. Default is
1/1, or no scaling. Currently, the supported scaling ratios are
M/N with all N from 1 to 16, where M is the destination DCT size,
which is 8 by default (see block_size parameter above).
(The library design allows for arbitrary scaling ratios but this
is not likely to be implemented any time soon.)
J_COLOR_SPACE jpeg_color_space
int num_components
The JPEG color space and corresponding number of components; see
"Special color spaces", below, for more info. We recommend using