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Compressing Images

This function can be used by coding or calling the API.

To save space, you can compress images that are output in JPG format. Table 1 describes the parameters in detail.

Operation name: quality

Table 1 Compression

Parameter

Value Description

Code Example

q

Relative quality of the image. The image is compressed to q% of the original. q ranges from 1 to 100.

Formula for compression: Target quality = Original quality x q%

For example, if the original quality of the image is 100% and the relative quality is 80%, then the target quality of the image is 80%. If the original quality of the image is 80% and the relative quality is 80%, then the target quality of the image is 64%.

image/resize,w_100,h_100/quality,q_80

Q

Absolute quality of the image. The image is compressed into Q%. Q is irrelevant to and does not depend on the original image. q ranges from 1 to 100.

Formula for compression:

  • When Original quality > Q%, Target quality = Q%.
  • When Original quality = Q%, Target quality = Original quality = Q%.
  • When Original quality < Q%, Target quality = Original quality.

For example, if the original quality of the image is 100% and the absolute quality is 80%, then the target quality of the image is 80%. If the original quality of the image is 70% and the absolute quality is 80%, then the target quality of the image is 70%.
  • q is valid only for JPG images.
  • If both q and Q are used, the output is based on Q.
  • q and Q are only valid for JPG images. For images in other formats, q and Q bring no effect and cause no impact.

Example