VipsWiki - Recent changes [en]

Build on OS X

2013-05-20T10:01:35Z

/* Homebrew */

Revision as of 10:01, 20 May 2013		Current revision
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	<pre>		<pre>
		+	$ brew tap homebrew/science
	$ brew install vips		$ brew install vips
		+	</pre>
		+
		+	To verify your vips install, try:
		+
		+	<pre>
		+	$ vips --version
		+	vips-7.32.1-Mon May 20 10:01:38 BST 2013
	</pre>		</pre>

	This is a good way to get libvips on your system, not so great for nip2.		This is a good way to get libvips on your system, not so great for nip2.
		+
		+	This will give you a very bare-bones vips, missing things like imagemagick loading, openslide support, FFTs, and so on. To get a list of all the optional dependencies, try:
		+
		+	<pre>
		+	$ brew info vips
		+	</pre>
		+
		+	For a full-fat version, try:
		+
		+	<pre>
		+	$ brew install vips --with-cfitsio --with-fftw --with-imagemagick \
		+	--with-libexif --with-liboil --with-libtiff --with-little-cms \
		+	--with-openexr --with-openslide --with-pango
		+	</pre>
		+
		+	If you want to build things outside homebrew which depend on vips, such as ruby-vips, you will need to get your pkg-config working. You need to point pkg-config at the homebrew area, and, additionally, at homebrew's libxml2 area:
		+
		+	In your .profile, add something like:
		+
		+	<pre>
		+	export PKG_CONFIG_PATH=/usr/local/lib/pkgconfig:/usr/local/opt/libxml2/lib/pkgconfig
		+	</pre>
		+
		+	To verify that pkg-config is working correctly with vips, try:
		+
		+	<pre>
		+	$ pkg-config vips --libs
		+	-L/usr/local/Cellar/vips/7.32.1/lib ... a lot of stuff
		+	</pre>

	=== Macports ===		=== Macports ===

	VIPS and nip2 are in [http://www.macports.org/ Macports], though it's an old version.		VIPS and nip2 are in [http://www.macports.org/ Macports], though it's an old version.

How it works

2013-05-17T12:48:24Z

/* Partial images */

Revision as of 12:48, 17 May 2013		Current revision
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	The stored function comes in three parts: a start function, a generate function and a stop function. The start function creates a state, the generate function uses the state plus a requested area to calculate pixel values and the stop function frees the state again. Breaking the stored function into three parts is good for SMP scaling: resource allocation and synchronisation mostly happens in start functions, so generate functions can run without having to talk to each other.		The stored function comes in three parts: a start function, a generate function and a stop function. The start function creates a state, the generate function uses the state plus a requested area to calculate pixel values and the stop function frees the state again. Breaking the stored function into three parts is good for SMP scaling: resource allocation and synchronisation mostly happens in start functions, so generate functions can run without having to talk to each other.

-	VIPS makes a set of guarantees about parallelism that make this simple to program. Start and stop functions are mutually exclusive and a state is never be used by more than one generate. In other words, a start / generate / generate / stop sequence works like a thread.	+	VIPS makes a set of guarantees about parallelism that make this simple to program. Start and stop functions are mutually exclusive and a state is never used by more than one generate. In other words, a start / generate / generate / stop sequence works like a thread.

	[[Image:Sequence.png]]		[[Image:Sequence.png]]

Speed and Memory Use

2013-05-17T11:27:21Z

/* Why is VIPS quick */

Revision as of 11:27, 17 May 2013		Current revision
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	We have a [[How it works]] page which goes into some detail, but briefly:		We have a [[How it works]] page which goes into some detail, but briefly:

-	; Threaded image IO system: most image processing libraries have threaded operations. Each operation has code, generally using a framework like OpenMP, to run the operation over all the available processors. VIPS instead puts the threading into the image IO system, so all operations are automatically threaded. Additionally, this type of "horizontal" threading makes much better use of processor caches and dramatically reduces the amount of locking you need.	+	; Threaded image input-output (IO) system: Most image processing libraries have threaded operations. Each operation has code, generally using a framework like OpenMP, to run the operation over all the available processors. VIPS instead puts the threading into the image IO system, so all operations are automatically threaded. Additionally, this type of "horizontal" threading makes much better use of processor caches and dramatically reduces the amount of locking you need.

	; Fast operations: The VIPS primitives are implemented carefully, and some use techniques like run-time code generation. The convolution operator, for example, will examine the matrix and the image and write a short SSE3 program to implement exactly that convolution on exactly that image.		; Fast operations: The VIPS primitives are implemented carefully, and some use techniques like run-time code generation. The convolution operator, for example, will examine the matrix and the image and write a short SSE3 program to implement exactly that convolution on exactly that image.