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JpegTurbo

This is a work-in-progress Julia package to provide Julia-callable wrappers to the libjpeg-turbo C library.

It currently only offers a very low-level mirror of the C API, but this should be a good starting point for higher-level Julia code.

Example usage to open a JPEG file and extract the image width from the header, based on the libjpeg documentation:

# download a test image:
using TestImages
filename = testimage("earth_apollo17", download_only=true)

# read the header and display the width:
import JpegTurbo: LibJpeg
cinfo = LibJpeg.jpeg_decompress_struct()
jerr = Ref{LibJpeg.jpeg_error_mgr}()
cinfo.err = LibJpeg.jpeg_std_error(jerr)
LibJpeg.jpeg_create_decompress(cinfo)
infile = ccall(:fopen, Libc.FILE, (Cstring, Cstring), filename, "rb")
LibJpeg.jpeg_stdio_src(cinfo, infile)
LibJpeg.jpeg_read_header(cinfo, true)
LibJpeg.jpeg_start_decompress(cinfo)
@show Int(cinfo.output_width) # show the image width
LibJpeg.jpeg_destroy_decompress(cinfo)
ccall(:fclose, Cint, (Ptr{Libc.FILE},), infile)