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Optimisation

Boot time

• give the user something to do during boot (fill out book title, ...) and he won't feel as if he's waiting

Time between triggerings

• single chdkptp triggering:
• pi ~4s (A1400, kariluoma)
• desktop ~3.75s (A1400, kariluoma)
• test:
• disk i/o bound?
• usb bound?
• ram disk

Testing

Testing reliability

• throw 1000 requests at the web interface and check the output

Testing performance

• pi max sustained wired network throughput ~4Mb/s:

dd if=/dev/zero over netcat
536870912 bytes (537 MB) copied, 135.758 s, 4.0 Mb/s
100mbit wired connection

• previews: downscale jpeg 4320x3240 -> 500x375:

• full image: 1.4Mb*2=2.8Mb wired network transfer at 4Mb/s~=0.7s

• downscaled preview: 50k wired network transfer neglegible= ~0.7s win

• pil, imagemagick: 5.2s

• epeg-cffi: 0.7s

• net effect to pc on wired LAN neutral (but faster rendering!)

• positive performance effect to tablet/phone/... or over wifi

• rotation:

• jpegtran does lossless jpeg rotation (fast, without decoding/reencoding)

• cropping:

• jpegtran (old python wrapper) does lossless jpeg cropping (fast along DCT boxes, without decoding/reencoding)

• deskewing:

• It probably makes sense to do this before feeding to tesseract since it would need to happen twice otherwise...

• unpaper

• leptonica

• imagemagick

• pamtilt (netpbm)

• scantailor-cli

• get public domain books

• scan and publish (github? ...)

• thumbnails for browser preview:

• epeg

• avoid temporary files (disk i/o!)

• bitonalisation (color -> b/w): unpaper,

Mount .img file

• losetup /dev/loop0 image.img
• kpartx -a /dev/loop0
• mount /dev/mapper/loop0p2 /mnt/test/
• To mount the boot partition, mount /dev/mapper/loop0p1