title: Python Examplespermalink: /Python_Examples/

getting started in Ubuntu

Average a region of interest box on an image

#!/usr/bin/env pythonimportsysfromvipsCCimport*roix=10roiy=10roiw=64roih=64try:a=VImage.VImage (sys.argv[1])roi=a.extract_area(roix,roiy,roiw,roih)print'average: ',roi.avg ()exceptVError.VError,e:e.perror (sys.argv[0])

VIPS and PIL

#!/usr/bin/pythonimportsysfromvipsCCimport*importImage# try this 1,000 times and check for leaksforiinrange (0,1000):vim=VImage.VImage (sys.argv[1])# do some processing in vips ... cut out a small piece of imagevim=vim.extract_area (500,500,100,100)# make a PIL image# we use Image.frombuffer (), so PIL is using vim's memory# you need to be very careful not to destroy vim until you're done with pim# ideally you should make a proxy class that wraps this lifetime problem upmode=VImage.PIL_mode_from_vips (vim)size= (vim.Xsize (),vim.Ysize ())data=vim.tobuffer ()pim=Image.frombuffer (mode,size,data,'raw',mode,0,1)# rotate 12 degrees with PILpim=pim.rotate (12,Image.BILINEAR,1)# back to vips again# PIL doesn't have a tobuffer method, so we have to use tostring to copy the# data out of PIL and then fromstring to copy back into VIPSstr=pim.tostring ()bands,format,type=VImage.vips_from_PIL_mode (pim.mode)width,height=pim.sizevim2=VImage.VImage.fromstring (str,width,height,bands,format)# finally write from vipsvim2.write (sys.argv[2])

Leak testing

#!/usr/bin/pythonimportsys# just need this for leaktestingimportgcfromvipsCCimport*iflen (sys.argv)!=3:print'usage:',sys.argv[0],'inputimage outputimage'sys.exit (1)try:a=VImage.VImage (sys.argv[1])b=a.invert ()c=b.lin ([1,2,3],[4,5,6])m=VMask.VIMask (3,3,1,0,          [-1,-1,-1,-1,8,-1,-1,-1,-1])d=a.conv (m)d.write (sys.argv[2])exceptVError.VError,e:e.perror (sys.argv[0])# we can get properties of VImage tooprint'inputimage is',a.Xsize (),'pixels across'print'starting shutdown ...'delbdeladelcdelddelm# sometimes have to do several GCs to get them all, not sure whyforiinrange(10):gc.collect ()print'shutdown!'print'leaked IMAGEs:'VImage.im__print_all ()print'done ... hopefully you saw no leaks'

Build image mosaic

#!/usr/bin/pythonimportsysimportrandomfromvipsCCimport*# the size of the image we buildsize=10000try:iflen(sys.argv)<3:print'usage:',sys.argv[0],'outfile infile1 ...'sys.exit (1)# make the background imagebg=VImage.VImage.black (size,size,3)# paste each argument inforfileinsys.argv[2:]:im=VImage.VImage (file)# is this a mono image? convert to RGB by joining three of them# togetherifim.Bands()==1:im=im.bandjoin (im).bandjoin (im)x=random.randint (0,size-im.Xsize ()-1)y=random.randint (0,size-im.Ysize ()-1)bg=bg.insert_noexpand (im,x,y)# write resultbg.write (sys.argv[1])exceptVError.VError,e:e.perror (sys.argv[0])

Build image pyramid

#!/usr/bin/pythonimportsysfromvipsCCimport*tilesize=512maxlevel=100try:im=VImage.VImage (sys.argv[1])forlevelinrange (maxlevel,-1,-1):print"Creating tiles for level",level# loop to create the tilesforyinrange (0,im.Ysize(),tilesize):forxinrange (0,im.Xsize(),tilesize):filename='%dx%d_y%d.jpg'% (level,x/tilesize,y/tilesize)# clip tilesize against image sizewidth=min (im.Xsize ()-x,tilesize)height=min (im.Ysize ()-y,tilesize)# expand edge tiles up to the full tilesize ... Google maps likes this# im.extract_area (x, y, width, height).embed(0, 0, 0, tilesize, tilesize).write(filename)# let edge tiles be smaller than the full tile size, tiff tiling prefers thisim.extract_area (x,y,width,height).write (filename)# was there only a single tile? we are doneifim.Xsize()<=tilesizeandim.Ysize()<=tilesize:break# create next pyramid level in RAMshrink=im.rightshift_size (1,1,im.BandFmt())im=shrink.write (VImage.VImage ("temp","t"))exceptVError.VError,e:e.perror (sys.argv[0])

Rename DICOM images using header fields

#!/usr/bin/pythonimportsysimportreimportosimportshutilfromvipsCCimport*iflen (sys.argv)!=3:print'rename DICOM files using tags from the header'print'usage:'print'\t%s srcdir destdir'%sys.argv[0]print'the directory tree below srcdir is searched, all files are'print'renamed and put into destdir in a flat list'sys.exit (1)srcdir=sys.argv[1]destdir=sys.argv[2]ifnotos.access (destdir,os.F_OK|os.R_OK|os.W_OK|os.X_OK):os.mkdir (destdir)defget_field (vim,field):result=vim.meta_get_string (field)# remove any \n etc.result=re.sub ("\n","",result)# remove any leading or trailing spacesresult=re.sub (" $","",result)result=re.sub ("^ ","",result)returnresultid_name="magick-dcm:Patient'sID"modality_name="magick-dcm:Modality"series_name="magick-dcm:SeriesNumber"instance_name="magick-dcm:Instance(formerlyImage)Number"date_name="magick-dcm:ImageDate"n_processed=0for (dirpath,dirnames,filenames)inos.walk (srcdir):forfileinfilenames:path=os.path.join (dirpath,file)try:vim=VImage.VImage (path)exceptVError.VError,e:print'unable to open',pathcontinuetry:id=get_field (vim,id_name)modality=get_field (vim,modality_name)series=get_field (vim,series_name)instance=get_field (vim,instance_name)date=get_field (vim,date_name)exceptVError.VError,e:print'unable to get fields from header',pathcontinuematch=re.match ("(\d\d\d\d)(\d\d)(\d\d)",date)date=match.group (1)+"."+match.group (2)+"."+match.group (3)newname=id+"."+modality+"."+series+"."+instance+"."+date+".IMA"shutil.copyfile(path,os.path.join (destdir,newname))n_processed+=1print'\t(%d files processed)'%n_processed