![]() ![]() ![]() For more precise control, you can use the PNG:compression-level=N, PNG:compression-strategy=N, and PNG:compression-filter=N defines, respectively, instead. Not all combinations of compression level, strategy, and PNG filter type can be obtained using the -quality option. The quality setting has no effect on the appearance or signature of PNG and MNG images, since the compression is always lossless. The default PNG "quality" is 75, which means compression level 7 with adaptive PNG filtering, unless the image has a color map, in which case it means compression level 7 with no PNG filtering.įor compression level 0 (quality value less than 10), the Huffman-only strategy is used, which is fastest but not necessarily the worst compression. A quality of 75 results in a request for 16:1 compression.įor the MNG and PNG image formats, the quality value sets the zlib compression level ( quality / 10) and filter-type ( quality % 10). The default quality value 100, a request for non-lossy compression. This non-linear equation is intended to loosely approximate the quality provided by the JPEG v1 format. Use the -sampling-factor option to specify the factors for chroma downsampling.įor the JPEG-2000 image format, quality is mapped using a non-linear equation to the compression ratio required by the Jasper library. When the quality is greater than 90, then the chroma channels are not downsampled. The default is to use the estimated quality of your input image if it can be determined, otherwise 92. The -quality option is applicable for JPEG, MIFF, TIFF, PNG, MNG formats.įor lossy image formats (JPEG), this option sets the degree of quality – the lower the quality, the greater the loss in compression, but also the smaller the size.įor other lossless encoding formats, this option sets the compression ratio.įor the JPEG and MPEG image formats, quality is 1 (lowest image quality and highest compression) to 100 (best quality but least effective compression). Magick IMAGE.jpg -quality 40 COMPRESSED.jpg For VALUE, enter a number between 1 (worst quality) and 100 (best quality). When converting to some formats, you can use the -quality VALUE option. How to set image compression level in Linux command line -resample GEOMETRY – changes image resolution, works with dpi.The key feature of -sample is that no new colors are added to the resulting image, although some colors may disappear. -sample GEOMETRY – modifies the image with pixel subsampling and pixel replication respectively.-resize GEOMETRY – resizes the image, takes into account filters (option -filter).In addition to this option, there are also the following: When you reduce an image, pixels are simply removed. The -scale option enlarges images using pixel averaging. See the Image Geometry section for details. That is, the image size is less than 500 pixels, then its width will be set to 500 pixels with the following command: If you use the command without the greater than sign ( >), the image size will be set to 500 pixels, regardless of its initial size. For example, the following command will only shrink an image to 500 pixels wide if the image is larger than 500 pixels. If you want the image to resize only if it is larger than a certain size, then use the -scale option with a greater than sign ( >), which must be enclosed in quotes along with the number. For details on installing ImageMagick, including which dependencies need to be installed to support the maximum number of formats, as well as a description of the command structure and all options, see the article: “ ImageMagick guide: installing, using, and troubleshooting”. The magick command is part of the ImageMagick package. Magick IMAGE.jpg -scale 150 COMPRESSED.jpg This option sets the width of the output image, as for the height, it will be selected automatically to maintain the original aspect ratio of the image. To specify the image size in pixels, use the magick utility with -scale PIXELS option. How to resize an image on the Linux command line This will affect the clarity of the image and the ability to see fine details. Increase the level of image compression (for images compressed with loss of quality, this will lead to a deterioration in the appearance of the image, for images compressed without quality loss, this will mean longer processing of the image)ģ. Select lossy image encoding format (JPEG)Ģ. You can reduce the image size in several ways:ġ. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |