サンプル
-quality
% convert -quality 70 a.jpg b.jpg
0〜100で指定。デフォルトは75。
リンク
パッケージ
help
mac% /usr/local/bin/convert -h Version: ImageMagick 5.5.7 11/01/03 Q16 http://www.imagemagick.org Copyright: Copyright (C) 2003 ImageMagick Studio LLC Usage: /usr/local/bin/convert [options ...] file [ [options ...] file ...] [options ...] file Where options include: -adjoin join images into a single multi-image file -affine matrix affine transform matrix -antialias remove pixel-aliasing -append append an image sequence -authenticate value decrypt image with this password -average average an image sequence -background color background color -black-threshold value forces all pixels below the threshold into black -blue-primary point chomaticity blue primary point -blur geometry blur the image -border geometry surround image with a border of color -bordercolor color border color -channel type extract a particular color channel from image -charcoal radius simulate a charcoal drawing -chop geometry remove pixels from the image interior -clip apply clipping path if the image has one -coalesce merge a sequence of images -colorize value colorize the image with the fill color -colors value preferred number of colors in the image -colorspace type alternate image colorspace -comment string annotate image with comment -compress type image compression type -contrast enhance or reduce the image contrast -convolve coefficients apply a convolution kernel to the image -crop geometry preferred size and location of the cropped image -cycle amount cycle the image colormap -debug events display copious debugging information -deconstruct break down an image sequence into constituent parts -delay value display the next image after pausing -density geometry horizontal and vertical density of the image -depth value image depth -despeckle reduce the speckles within an image -display server get image or font from this X server -dispose method Undefined, None, Background, Previous -dither apply Floyd/Steinberg error diffusion to image -draw string annotate the image with a graphic primitive -edge radius apply a filter to detect edges in the image -emboss radius emboss an image -encoding type text encoding type -endian type LSB or MSB -enhance apply a digital filter to enhance a noisy image -equalize perform histogram equalization to an image -extract geometry extract area from image -fill color color to use when filling a graphic primitive -filter type use this filter when resizing an image -flatten flatten a sequence of images -flip flip image in the vertical direction -flop flop image in the horizontal direction -font name render text with this font -frame geometry surround image with an ornamental border -fuzz distance colors within this distance are considered equal -gamma value level of gamma correction -gaussian geometry gaussian blur an image -geometry geometry perferred size or location of the image -green-primary point chomaticity green primary point -gravity type horizontal and vertical text placement -help print program options -implode amount implode image pixels about the center -intent type Absolute, Perceptual, Relative, or Saturation -interlace type None, Line, Plane, or Partition -label name assign a label to an image -lat geometry local adaptive thresholding -level value adjust the level of image contrast -limit type value Disk, Map, or Memory resource limit -list type Color, Delegate, Format, Magic, Module, Resource, or Type -log format format of debugging information -loop iterations add Netscape loop extension to your GIF animation -map filename transform image colors to match this set of colors -mask filename set the image clip mask -matte store matte channel if the image has one -median radius apply a median filter to the image -modulate value vary the brightness, saturation, and hue -monochrome transform image to black and white -morph value morph an image sequence -mosaic create a mosaic from an image sequence -negate replace every pixel with its complementary color -noop do not apply options to image -noise radius add or reduce noise in an image -normalize transform image to span the full range of colors -opaque color change this color to the fill color -ordered-dither channeltype LOWxHIGH ordered dither the image -page geometry size and location of an image canvas -paint radius simulate an oil painting -ping efficiently determine image attributes -pointsize value font point size -preview type image preview type -profile filename add ICM or IPTC information profile to image -quality value JPEG/MIFF/PNG compression level -raise value lighten/darken image edges to create a 3-D effect -random-threshold channeltype LOWxHIGH random threshold the image -region geometry apply options to a portion of the image -raise value lighten/darken image edges to create a 3-D effect -red-primary point chomaticity red primary point -render render vector graphics -resize geometry resize the image -resample geometry change the resolution of an image -roll geometry roll an image vertically or horizontally -rotate degrees apply Paeth rotation to the image -sample geometry scale image with pixel sampling -sampling-factor geometry horizontal and vertical sampling factor -scale geometry scale the image -scene value image scene number -seed value pseudo-random number generator seed value -segment values segment an image -shade degrees shade the image using a distant light source -sharpen geometry sharpen the image -shave geometry shave pixels from the image edges -shear geometry slide one edge of the image along the X or Y axis -size geometry width and height of image -solarize threshold negate all pixels above the threshold level -spread amount displace image pixels by a random amount -stroke color graphic primitive stroke color -strokewidth value graphic primitive stroke width -swirl degrees swirl image pixels about the center -texture filename name of texture to tile onto the image background -threshold value threshold the image -thumbnail geometry create a thumbnail of the image -tile filename tile image when filling a graphic primitive -transform affine transform image -transparent color make this color transparent within the image -treedepth value color tree depth -trim trim image edges -type type image type -undercolor color annotation bounding box color -units type PixelsPerInch, PixelsPerCentimeter, or Undefined -unsharp geometry sharpen the image -verbose print detailed information about the image -version print version information -view FlashPix viewing transforms -virtual-pixel method Constant, Edge, Mirror, or Tile -wave geometry alter an image along a sine wave -white-point point chomaticity white point -white-threshold value forces all pixels above the threshold into white -write filename write images to this file By default, the image format of `file' is determined by its magic number. To specify a particular image format, precede the filename with an image format name and a colon (i.e. ps:image) or specify the image type as the filename suffix (i.e. image.ps). Specify 'file' as '-' for standard input or output.
