The quality adjustment operation uses the format of a source image to compress the image. You can use the quality adjustment parameters to modify the quality of source images stored in Object Storage Service (OSS). This topic describes the parameters and examples for image quality adjustment.
Quality adjustment applies only to JPG and WebP images.
Parameters
Operation name: quality
The following table describes the parameters that you can configure when you adjust the quality of an image.
Parameter | Description | Valid value |
---|---|---|
q | Specifies the relative quality of the image and compresses the source image based
on percentage.
If the source image quality is 100%, you can obtain an image whose quality value is
90% after you add the Note The q parameter applies only to source images in the JPG format to specify the relative
quality of the images. If a source image is in the WebP format, this parameter works
the same as Q. The absolute quality is specified for the image.
|
[1,100] |
Q | Specifies the absolute quality of the image and compresses the source image based
on Q%. If the quality value of the source image is smaller than the specified Q value,
the quality value of the compressed image is the quality value of the source image.
For example, if the quality value of the source image is 95%, you can obtain an image
that has a quality value of 90% after you add Note The Q parameter applies only to JPG and WebP images.
|
[1,100] |
Examples
You can process images by using object URLs, OSS SDKs, or API operations. In this example, object URLs are used. For more information about how to use OSS SDKs and API operations to process images, see IMG implementation modes.
An image in the bucket named oss-console-img-demo-cn-hangzhou in the China (Hangzhou) region is used in the following examples. The following URL is used to access the image over the Internet:
- Adjust the relative quality of an image
Configure the parameters based on the following requirements:
- Resize the image to a width of 100 pixels:
resize,w_100
- Set the relative quality value of the image to 80%:
quality,q_80
The URL used to process the image is in the following format: https://oss-console-img-demo-cn-hangzhou.oss-cn-hangzhou.aliyuncs.com/example.jpg?x-oss-process=image/resize,w_100/quality,q_80 - Resize the image to a width of 100 pixels:
- Adjust the absolute quality of an image
Configure the parameters based on the following requirements:
- Resize the image to a width of 100 pixels:
resize,w_100
- Set the absolute quality value of the image to 80%:
quality,Q_80
The URL used to process the image is in the following format: https://oss-console-img-demo-cn-hangzhou.oss-cn-hangzhou.aliyuncs.com/example.jpg?x-oss-process=image/resize,w_100/quality,Q_80 - Resize the image to a width of 100 pixels: