You can read more about them here: How to optimize images on Linux Image sharpening basics In the first part of the article, we’ve looked at Image Magick usage, removing sensitive information from images, and geometry reduction techniques. To reduce png file's size when reducing color, use -depth for values of to stand for file name.There are a few advanced tricks to optimize images for web consumption, such as sharpening them after size reduction and using dedicated command-line tools to reduce their sizes. Note that reducing colors does not necessarily reduce file size. To reduce color without dithering, use +dither instead of -dither. Reduce color magick convert -dither -colors 256 old.png new.png That makes it 8 bits.įor clean black and white line art, you can use “-depth 2”. In particular, for a grayscale line art in png, you can do: Note: this does not force the png image format to use indexed color for smaller file size. Transparency, Color, Bits Per Pixel remove transparency/alpha with white magick convert -flatten old.png new.png to gray scale magick convert -type Grayscale old.png new.png The above increase color saturation by the multiplier 130%. saturation magick convert -modulate 100,130,100 old.png new.png The 3 numbers means: brightness, saturation, hue.
The above increase brightness by the multiplier 150%.
Color, Brightness, Saturation brightness magick convert -modulate 150,100,100 old.png new.png To crop by specifying percentage of sides to cut, use “-shave”. The x and y axes's origin starts at the upper left corner. The 0 is the offset on x-axis, and 56 is the offset of y-axis. The 853 and 368 would be the new image's width and height. Scale, Crop scale magick convert -scale 50% x1.jpg x2.pngĪutocrop magick convert -trim x.png x.png crop magick convert -crop 853x368+0+56 old.png new.png Each time you save to JPG, it loses some info. ForĮxample, converting from png to gif may loseĬolors because gif only support a max of 256 colors. The format you are converting from, otherwise you may lose info. Remember, the destination format should support all the features of This page shows you how to do common image editing tasks using the command line software ImageMagick.įind version magick -version jpg png Conversion gif to png magick convert p1.gif p2.png png to jpg magick convert -quality 90% old.png new.jpg
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