Legacy ImageMagick Discussions Archive

What is the command for increasing the image Brightness, Contrast, Hue and Saturation ?

http://www.imagemagick.org/script/comma ... s-contrast
http://www.imagemagick.org/script/comma ... p#modulate

You can also use -level and -sigmoidal-contrast to affect brightness and contrast. Also -evaluate multiply and -gamma as well.

see
http://www.imagemagick.org/Usage/color_mods/#level
http://www.imagemagick.org/Usage/color_ ... evel_gamma
http://www.imagemagick.org/Usage/color_mods/#sigmoidal

Some of the above are linear and others non-linear. There are lots of ways to affect brightness and contrast.

For a general review see http://www.imagemagick.org/Usage/color_mods/

For some one relatively new to Imagemagick, I would recommend

http://www.imagemagick.org/Usage/reference.html
http://www.imagemagick.org/Usage/

I am using below two commands for Brightness, Contrast Saturation and Hue

convert bw.jpg -brightness-contrast 0,100 bw1.jpg

0 = Brightness
100 = Contrast

convert bw.jpg -modulate 150,100,180 bw1.jpg

150 = Brightness
100 = Saturation
180 = Hue

My question is, can i use negative values like -150, -10 - 67 as values for Brightness, Saturation and Hue ?

-brightness-contrast allows negative values. -modulate does not. -modulate 100,100,100 is not change so to reduce brightness or saturation, use values less than 100.

see
http://www.imagemagick.org/script/comma ... p#modulate
http://www.imagemagick.org/script/comma ... s-contrast

Thank you