You can add Image Processing (IMG) parameters in the GetObject operation to process image objects stored in OSS. For example, you can add image watermarks or convert image formats.


OSS allows you to directly use one or more parameters to process images, or encapsulate multiple IMG parameters in a style to process multiple images at a time. OSS processes the images in the order of the parameters when multiple IMG parameters exist. The following table lists the parameters of IMG.

IMG operation Parameter Description
Resize images resize Resizes images to a specified size.
Incircle circle Crops images based on the center point of images to ellipses of the specified size.
Custom crop crop Crops rectangular images of the specified size.
Indexed cut indexcrop Cuts images along the specified horizontal or vertical axis and selects one of the images.
Rounded rectangle rounded-corners Crops images to rounded rectangles based on the specified rounded corner size.
Automatic rotation auto-orient Auto-rotates images that include the auto-orient parameter.
Rotate rotate Rotates images clockwise based on the specified angle.
Blur blur Blurs images.
Brightness bright Adjusts the brightness of images.
Sharpen sharpen Sharpens images.
Contrast contrast Adjusts the contrast of images.
Gradual display interlace Configures gradual display for the JPG images.
Quality transformation quality Adjusts the quality of images in the JPG and WebP formats.
Format conversion format Converts image formats.
Add watermarks watermark Adds image or text watermarks to images.
Query the average tone average-hue Queries the average tone of images.
Query image information info Queries image information, including basic information and EXIF information.

We recommend that you use image style to process multiple images at a time. For more information, see Image style.

Implementation methods

You can use object URLs, API operations, and SDKs to process images. For more information, see IMG implementation modes.


When you use IMG, take note of the following items:
  • Limits on source images
    • Only JPG, PNG, BMP, GIF, WebP, and TIFF images are supported.
    • The size of the image object cannot exceed 20 MB.
    • The width or height of the source image cannot exceed 4,096 pixels when you rotate images.
    • Each side of the source image cannot exceed 30,000 pixels.
    • The source image cannot exceed 250 million pixels in total.

      The pixel number of a static image is calculated by using the following formula: Width x Height. The pixel number of a dynamic image, such as a GIF image, is calculated by using the following formula: Width x Height x Number of image frames.

  • Limits on resized images
    • Each side of a resized image cannot exceed 16,384 pixels.
    • The image cannot exceed 16,777,216 pixels in total.
  • Limits on image styles

    You can create up to 50 image styles in each bucket. If you need to create more than 50 styles, contact technical support.


IMG provides two API versions: the later API version and the earlier API version. This topic describes the APIs of the later version. The APIs of the earlier version are not updated. For more information about the compatibility between the later and earlier versions of APIs, see FAQ on using old and new versions of APIs and domain names.