Re: Precise bitmaps

*To*: mathgroup at smc.vnet.net*Subject*: [mg96723] Re: Precise bitmaps*From*: lehin.p at gmail.com*Date*: Sun, 22 Feb 2009 03:12:28 -0500 (EST)*References*: <gnq6ni$83g$1@smc.vnet.net>

On 22 =C6=C5=D7, 03:37, "Diamond, Mark" <d... at dot.dot> wrote: > A question was asked back in 2005 about precise bitmaps. I have a similar > question with regard to Mathematica version 7. > > Looking at the new image-manipulation functions in V7, I expected this to= be > quick ... I'd like to be able to create a series of stimuli for use in an > experiment. The first step in creating the stimuli is to create a 512 x 5= 12 > greyscale image with a white background and which contains the drawn > objects. > > I tried the following to create a JPEG image with dimensions 128x128 ... > > circ=Graphics[Circle[{0,0},62]] > rasterCirc=Rasterize[circ,RasterSize->{128,128}] > Export["circle.jpg",rasterCirc] > > but instead the image dimensions are 360 x 363 pixels. I had also hoped t= hat > I could obtain an antialiased arc but the only antialiasing option seems = to > be for Style, which then produces a non-Graphics object. > > Can anyone see a simple (i.e., not very low-level programming) solution t= o > the problem within Mathematica? What have I missed conceptually that woul= d > explain the 360x363 pixel dimensions instead of my expected 128x128? And = is > there a way to obtain the anti-aliased circle? > > Cheers, > > Mark Diamond Hello, The solution for your problem is: circ = Graphics[Style[Circle[{0, 0}, 62], Antialiasing -> True], ImageSize -> {128, 128}] Export["circle.jpg", circ, "Smoothing" -> 0, "CompressionLevel" -> 0] The default "Automatic" value of the option ImageSize results in producing raster graphics with 360 pixels width. This is undocumented behavior and I do not know how to change it: http://tinyurl.com/bl6jjg http://tinyurl.com/cwgbky