Since libjpeg 7, decompression scaling factors of [1,16]/8 have
been supported. Upscaling is slower, but using the entire range
of downscaling factors is significantly faster for sizes between
the power-of-two factors.
Time to decompress a 5184x3456 image and scale to 1900x1200,
slightly less than 3/8ths, changes from 251ms to 203ms.
libjpeg versions prior to 7 will round up to the next largest
factor they support, and continue to work as before.
Change-Id: I00a0655df2ef057e739927a643bfe0b0cabd5602
Reviewed-by: Robin Burchell <robin+qt@viroteck.net>
Reviewed-by: aavit <qt_aavit@ovi.com>