Help Center/ Object Storage Service/ Image Processing (Paris Region)/ Changing Quality
Updated on 2024-02-29 GMT+08:00
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Changing Quality

You can edit code on OBS Console or make an API call to change the quality of an image.

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

Operation name: quality

Table 1 Compression description

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

  • Resize the image by setting the height and width both to 100, and output a jpg image with relative quality of 80%.

    https://obs.region.example.com/image-demo/example.jpg?x-image-process=image/resize,w_100,h_100/quality,q_80

  • Resize the image by setting the height and width both to 100, and output a jpg image with absolute quality of 80%.

    https://obs.region.example.com/image-demo/example.jpg?x-image-process=image/resize,w_100,h_100/quality,Q_80