用imageMagick的composite合并图片

composite命令可以非常方便的合并两张图片

因此用来进行图像加水印、批量增加边框等常用的变换

 

最简单的用法为：

composite -gravity north src.jpg coverback.jpg des.jpg

 

其中src.jpg为前景图片

coverback.jpg为背景图片。

des.jpg为叠加后的结果

 

-gravity north 指叠加位置为垂直据顶部、水平居中（正北方向）

如果要求在正中间，参数为center

如果要求在右下角，参数为southeast

 

composite还提供更灵活的定位，可以使用 -geometry 配置

 

具体的composite参数表见下表

 

-affine matrix	affine transform matrix
-alpha	on, activate, off, deactivate, set, opaque, copy", transparent, extract, background, or shape the alpha channel
-authenticate value	decrypt image with this password
-blend geometry	blend images
-blue-primary point	chromaticity blue primary point
-border geometry	surround image with a border of color
-bordercolor color	border color
-channel type	apply option to select image channels
-colors value	preferred number of colors in the image
-colorspace type	set image colorspace
-comment string	annotate image with comment
-compose operator	set image composite operator
-compress type	image compression type
-debug events	display copious debugging information
-decipher filename	convert cipher pixels to plain
-define format:option	define one or more image format options
-density geometry	horizontal and vertical density of the image
-depth value	image depth
-displace geometry	shift image pixels defined by a displacement map
-dissolve value	dissolve the two images a given percent
-dither method	apply error diffusion to image
-encipher filename	convert plain pixels to cipher pixels
-encoding type	text encoding type
-endian type	endianness (MSB or LSB) of the image
-extract geometry	extract area from image
-filter type	use this filter when resizing an image
-font name	render text with this font
-geometry geometry	preferred size or location of the image
-gravity type	horizontal and vertical text placement
-green-primary point	chromaticity green primary point
-help	print program options
-identify	identify the format and characteristics of the image
-interlace type	type of image interlacing scheme
-interpolate method	pixel color interpolation method
-label string	assign a label to an image
-level value	adjust the level of image contrast
-limit type value	pixel cache resource limit
-log format	format of debugging information
-monitor	monitor progress
-monochrome	transform image to black and white
-negate	replace each pixel with its complementary color
-page geometry	size and location of an image canvas (setting)
-pointsize value	font point size
-profile filename	add, delete, or apply an image profile
-quality value	JPEG/MIFF/PNG compression level
-quantize colorspace	reduce image colors in this colorspace
-quiet	suppress all warning messages
-red-primary point	chromaticity red primary point
-regard-warnings	pay attention to warning messages.
-respect-parentheses	settings remain in effect until parenthesis boundary.
-rotate degrees	apply Paeth rotation to the image
-sampling-factor geometry	horizontal and vertical sampling factor
-scene value	image scene number
-seed value	seed a new sequence of pseudo-random numbers
-set attribute value	set an image attribute
-sharpen geometry	sharpen the image
-shave geometry	shave pixels from the image edges
-size geometry	width and height of image
-stegano offset	hide watermark within an image
-stereo geometry	combine two image to create a stereo anaglyph
-strip	strip image of all profiles and comments
-swap indexes	swap two images in the image sequence
-synchronize	synchronize image to storage device
-taint	mark the image as modified
-thumbnail geometry	create a thumbnail of the image
-tile	repeat composite operation across and down image
-transform	affine transform image
-transparent-color color	transparent color
-treedepth value	color tree depth
-type type	image type
-units type	the units of image resolution
-unsharp geometry	sharpen the image
-verbose	print detailed information about the image
-version	print version information
-virtual-pixel method	access method for pixels outside the boundaries of the image
-watermark geometry	percent brightness and saturation of a watermark
-white-point point	chromaticity white point
-white-threshold value	force all pixels above the threshold into white
-write filename	write images to this file