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@FranckFreiburger
FranckFreiburger / getJpegQuality.js
Created Oct 4, 2018
pure JavaScript jpeg quality value recover
View getJpegQuality.js
// javascript jpeg decoder: https://github.com/eugeneware/jpeg-js/blob/79c4c7ea876d2e7b46981a563fcc4ae8f9e19849/lib/decoder.js
// Determine the JPEG compression quality from the quantization tables: https://github.com/ImageMagick/ImageMagick/blob/59f28acff016f6ae5e8b7e6300bcdf97e94affc9/coders/jpeg.c#L879
// JPEG File Layout and Format: http://vip.sugovica.hu/Sardi/kepnezo/JPEG%20File%20Layout%20and%20Format.htm
// jpeg constants: https://github.com/LuaDist/libjpeg/blob/6c0fcb8ddee365e7abc4d332662b06900612e923/jpeglib.h#L45
function getQuantizationTables(data) {
var quantizationTables = []
var dctZigZag = new Int32Array([
@justinko
justinko / callback_disabler.rb
Created Sep 2, 2011
Disable raw filter callbacks in RSpec
View callback_disabler.rb
# In spec/support/callback_disabler.rb
module CallbackDisabler
def self.store_callbacks(model, filters)
model = constantize(model)
filters.each do |filter|
model.send("_#{filter}_callbacks").each do |callback|
stored_callbacks[model] << {
filter: filter, kind: callback.kind, raw_filter: callback.raw_filter
}