This article will help you to get familiar with the recommended compression parameters while configuring the Import_Multipage_Files Plugin via ImagicMagick in the Folder Import module.
ImageMagick provides various compression parameters to compress an image:
- For uncompressed images, suitable ImageMagick compress parameters should be used that will reduce the size of image. For colored images ‘-compress LZW’, ‘-compress JPEG’ can be used and for black-white images ‘-compress Group4’ can be used.
- For already compressed images, same compression parameter should be used with ImageMagick that was used earlier to compress the original image. For instance, for already compressed images with JPEG compression, ‘-compress JPEG’ parameter should be used with ImageMagick too. This might increase the size of the image by a small delta but will maintain the consistency in quality.
- For good quality single page tiff files, ‘–quality’, ‘-depth’, ‘-scale’ parameters can be used that will reduce the size of the image depending on the use case. In case where compression is done with image depth, ‘–depth 1’ can be used which gives black and white images, and is faster than applying compression on black-white images using ‘-compress Group4’.
- In case resolution of image is extremely high then same image can also be resized i.e. if the image is above a particular threshold of resolution then it can be resized to the threshold resolution to reduce the size and even speed up the OCR process.
For more information on ImageMagick compression parameters, refer: http://www.imagemagick.org/script/command-line-options.php#compress