PDF compress command line provides two ways to reduce the file size, one is to remove redundancy information, and the other is to compress image by using the standard compression algorithms. It is an advanced tool tailored for your swift and high-level optimizing pdf file. Compared with other tools, it holds a striking advantage, reducing pdf size while maintaining accessibility and search engine visibility. This part serves as compressing image.
There are three kinds of image, color, gray and monochrome, and each can be set the compression format, quality and image scale size.
compressformat=compressformatvalue
quality=qualityvalue
imagesize=imagesizevalue
where
- the parameter compressformat is to choose a compression algorithm such as Flate, JPEG, CCITT, etc.,
- the parameter quality is to specify the image compressing quality,
- the imagesize is to specify the scale ratio to the image.
The compressformatvalue, qualityvalue and imagesizevlaue are the number to set the value of parameters, respectively.
- Color image
compressformat=3
0: Not change; 1: Flate compression; 2: JPEG compression; 3: JPEG2000 compression
where 0 is the default value.
quality=40
Set quality to color image, the value is from 1 to 100
where 100 is the default value.
imagesize=70
Set scale ratio to color image, the value is from 1 to 100
where 100 is the default value.
- Gray image
compressformat=2
0: original, 1:Flate, 2:JPEG
where 0 is the default value.
quality=20
Set quality to gray image, the value is from 1 to 100
where 100 is the default value.
imagesize=70
Set scale ratio to gray images, from 1 to 100
where 100 is the default value.
- Monochrome image
compressformat=2
0: Not change; 1: Flate compression; 2: CCITT Group4 compression
where 0 is the default value.
quality=60
Set quality to monochrome image, the value is from 1 to 100
where 100 is the default value.
imagesize=70
Set scale ratio to black and white image, the value is from 1 to 100
where 100 is the default value.
If you have one of them need, you can choose the corresponding parameter to compress image, for detailed operation, you are allowed to refer to the article posted here https://www.verypdf.com/wordpress/author/icarus.