pub fn imwrite_def(filename: &str, img: &impl ToInputArray) -> Result<bool>Expand description
Saves an image to a specified file.
The function imwrite saves the image to the specified file. The image format is chosen based on the filename extension (see cv::imread for the list of extensions). In general, only 8-bit unsigned (CV_8U) single-channel or 3-channel (with ‘BGR’ channel order) images can be saved using this function, with these exceptions:
- With OpenEXR encoder, only 32-bit float (CV_32F) images can be saved.
- 8-bit unsigned (CV_8U) images are not supported.
- With Radiance HDR encoder, non 64-bit float (CV_64F) images can be saved.
- All images will be converted to 32-bit float (CV_32F).
- With JPEG 2000 encoder, 8-bit unsigned (CV_8U) and 16-bit unsigned (CV_16U) images can be saved.
- With JPEG XL encoder, 8-bit unsigned (CV_8U), 16-bit unsigned (CV_16U) and 32-bit float(CV_32F) images can be saved.
- JPEG XL images with an alpha channel can be saved using this function. To achieve this, create an 8-bit 4-channel (CV_8UC4) / 16-bit 4-channel (CV_16UC4) / 32-bit float 4-channel (CV_32FC4) BGRA image, ensuring the alpha channel is the last component. Fully transparent pixels should have an alpha value of 0, while fully opaque pixels should have an alpha value of 255/65535/1.0.
- With PAM encoder, 8-bit unsigned (CV_8U) and 16-bit unsigned (CV_16U) images can be saved.
- With PNG encoder, 8-bit unsigned (CV_8U) and 16-bit unsigned (CV_16U) images can be saved.
- PNG images with an alpha channel can be saved using this function. To achieve this, create an 8-bit 4-channel (CV_8UC4) / 16-bit 4-channel (CV_16UC4) BGRA image, ensuring the alpha channel is the last component. Fully transparent pixels should have an alpha value of 0, while fully opaque pixels should have an alpha value of 255/65535(see the code sample below).
- With PGM/PPM encoder, 8-bit unsigned (CV_8U) and 16-bit unsigned (CV_16U) images can be saved.
- With TIFF encoder, 8-bit unsigned (CV_8U), 8-bit signed (CV_8S),
16-bit unsigned (CV_16U), 16-bit signed (CV_16S),
32-bit signed (CV_32S),
32-bit float (CV_32F) and 64-bit float (CV_64F) images can be saved.
- Multiple images (vector of Mat) can be saved in TIFF format (see the code sample below).
- 32-bit float 3-channel (CV_32FC3) TIFF images will be saved using the LogLuv high dynamic range encoding (4 bytes per pixel)
- With GIF encoder, 8-bit unsigned (CV_8U) images can be saved.
- GIF images with an alpha channel can be saved using this function. To achieve this, create an 8-bit 4-channel (CV_8UC4) BGRA image, ensuring the alpha channel is the last component. Fully transparent pixels should have an alpha value of 0, while fully opaque pixels should have an alpha value of 255.
- 8-bit single-channel images (CV_8UC1) are not supported due to GIF’s limitation to indexed color formats.
If the image format is not supported, the image will be converted to 8-bit unsigned (CV_8U) and saved that way.
If the format, depth or channel order is different, use Mat::convertTo and cv::cvtColor to convert it before saving. Or, use the universal FileStorage I/O functions to save the image to XML or YAML format.
The sample below shows how to create a BGRA image, how to set custom compression parameters and save it to a PNG file. It also demonstrates how to save multiple images in a TIFF file: @include snippets/imgcodecs_imwrite.cpp
§Parameters
- filename: Name of the file.
- img: (Mat or vector of Mat) Image or Images to be saved.
- params: Format-specific parameters encoded as pairs (paramId_1, paramValue_1, paramId_2, paramValue_2, … .) see cv::ImwriteFlags
§Note
This alternative version of imwrite function uses the following default values for its arguments:
- params: std::vector
()