How to use the command `dwebp` (with examples)

The dwebp command is used to decompress WebP files into PNG, PAM, PPM, or PGM images. It does not support animated WebP files. This command is useful for converting WebP images to other image formats.

Use case 1: Convert a webp file into a png file

Code:

dwebp path/to/input.webp -o path/to/output.png

Motivation: This use case is useful when you want to convert a WebP image to a PNG format, which is widely supported by various applications and web browsers.

Explanation:

• path/to/input.webp: Specifies the path of the input WebP image file.
• -o path/to/output.png: Specifies the path and filename for the output PNG file.

Example output: The input.webp file will be converted to output.png.

Use case 2: Convert a webp file into a specific filetype

Code:

dwebp path/to/input.webp -bmp|-tiff|-pam|-ppm|-pgm|-yuv -o path/to/output

Motivation: This use case allows you to convert a WebP image to a specific file format other than PNG. This can be useful when you need to use a specific image format that is compatible with a particular application or use case.

Explanation:

• -bmp|-tiff|-pam|-ppm|-pgm|-yuv: Specifies the desired output file format. Choose one of these options based on your requirements.
• -o path/to/output: Specifies the path and filename for the output file.

Example output: The input.webp file will be converted to the specified output file format.

Use case 3: Convert a webp file, using multi-threading if possible

Code:

dwebp path/to/input.webp -o path/to/output.png -mt

Motivation: This use case enables multi-threading during the conversion process, which can significantly improve the conversion speed, especially if you have a multi-core processor.

Explanation:

• -mt: Enables multi-threading during the conversion process.
• path/to/input.webp: Specifies the path of the input WebP image file.
• -o path/to/output.png: Specifies the path and filename for the output PNG file.

Example output: The input.webp file will be converted to output.png using multi-threading if possible.

Use case 4: Convert a webp file, but also crop and scale at the same time

Code:

dwebp input.webp -o output.png -crop x_pos y_pos width height -scale width height

Motivation: This use case allows you to crop and scale a WebP image during the conversion process. This can be useful when you want to extract a specific region of the image or resize it to a different dimension.

Explanation:

• -crop x_pos y_pos width height: Specifies the cropping parameters, where x_pos and y_pos are the coordinates of the top-left corner of the cropping region, and width and height are the dimensions of the cropped region.
• -scale width height: Specifies the scaling parameters, where width and height are the desired dimensions of the output image.
• input.webp: Specifies the path of the input WebP image file.
• -o output.png: Specifies the path and filename for the output PNG file.

Example output: The input.webp file will be converted to output.png after applying the crop and scale transformations.

Use case 5: Convert a webp file and flip the output

Code:

dwebp path/to/input.webp -o path/to/output.png -flip

Motivation: This use case allows you to flip the output image vertically during the conversion process. This can be useful when you want to reverse the orientation of the image.

Explanation:

• -flip: Flips the output image vertically.
• path/to/input.webp: Specifies the path of the input WebP image file.
• -o path/to/output.png: Specifies the path and filename for the output PNG file.

Example output: The input.webp file will be converted to output.png with a vertically flipped orientation.

Use case 6: Convert a webp file and don’t use in-loop filtering to speed up the decoding process

Code:

dwebp path/to/input.webp -o path/to/output.png -nofilter

Motivation: This use case disables in-loop filtering during the decoding process, which can improve the decoding speed but may result in slightly reduced image quality.

Explanation:

• -nofilter: Disables in-loop filtering.
• path/to/input.webp: Specifies the path of the input WebP image file.
• -o path/to/output.png: Specifies the path and filename for the output PNG file.

Example output: The input.webp file will be converted to output.png without using in-loop filtering.