tnew - plan9port - [fork] Plan 9 from user space
(HTM) git clone git://src.adamsgaard.dk/plan9port
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---
(DIR) commit acf8398fefe0b59da1ad20d06de5b11de3bdbc53
(DIR) parent 37052ddc266b4708c0629bc976b975091a195b3d
(HTM) Author: rsc <devnull@localhost>
Date: Sun, 19 Mar 2006 06:11:32 +0000
new
Diffstat:
A src/cmd/resample.c | 327 +++++++++++++++++++++++++++++++
1 file changed, 327 insertions(+), 0 deletions(-)
---
(DIR) diff --git a/src/cmd/resample.c b/src/cmd/resample.c
t@@ -0,0 +1,327 @@
+#include <u.h>
+#include <libc.h>
+#include <draw.h>
+#include <memdraw.h>
+
+#define K2 7 /* from -.7 to +.7 inclusive, meaning .2 into each adjacent pixel */
+#define NK (2*K2+1)
+double K[NK];
+
+double
+fac(int L)
+{
+ int i, f;
+
+ f = 1;
+ for(i=L; i>1; --i)
+ f *= i;
+ return f;
+}
+
+/*
+ * i0(x) is the modified Bessel function, Σ (x/2)^2L / (L!)²
+ * There are faster ways to calculate this, but we precompute
+ * into a table so let's keep it simple.
+ */
+double
+i0(double x)
+{
+ double v;
+ int L;
+
+ v = 1.0;
+ for(L=1; L<10; L++)
+ v += pow(x/2., 2*L)/pow(fac(L), 2);
+ return v;
+}
+
+double
+kaiser(double x, double tau, double alpha)
+{
+ if(fabs(x) > tau)
+ return 0.;
+ return i0(alpha*sqrt(1-(x*x/(tau*tau))))/i0(alpha);
+}
+
+void
+usage(void)
+{
+ fprint(2, "usage: resample [-x xsize] [-y ysize] [imagefile]\n");
+ fprint(2, "\twhere size is an integer or a percentage in the form 25%%\n");
+ exits("usage");
+}
+
+int
+getint(char *s, int *percent)
+{
+ if(s == nil)
+ usage();
+ *percent = (s[strlen(s)-1] == '%');
+ if(*s == '+')
+ return atoi(s+1);
+ if(*s == '-')
+ return -atoi(s+1);
+ return atoi(s);
+}
+
+void
+resamplex(uchar *in, int off, int d, int inx, uchar *out, int outx)
+{
+ int i, x, k;
+ double X, xx, v, rat;
+
+
+ rat = (double)inx/(double)outx;
+ for(x=0; x<outx; x++){
+ if(inx == outx){
+ /* don't resample if size unchanged */
+ out[off+x*d] = in[off+x*d];
+ continue;
+ }
+ v = 0.0;
+ X = x*rat;
+ for(k=-K2; k<=K2; k++){
+ xx = X + rat*k/10.;
+ i = xx;
+ if(i < 0)
+ i = 0;
+ if(i >= inx)
+ i = inx-1;
+ v += in[off+i*d] * K[K2+k];
+ }
+ out[off+x*d] = v;
+ }
+}
+
+void
+resampley(uchar **in, int off, int iny, uchar **out, int outy)
+{
+ int y, i, k;
+ double Y, yy, v, rat;
+
+ rat = (double)iny/(double)outy;
+ for(y=0; y<outy; y++){
+ if(iny == outy){
+ /* don't resample if size unchanged */
+ out[y][off] = in[y][off];
+ continue;
+ }
+ v = 0.0;
+ Y = y*rat;
+ for(k=-K2; k<=K2; k++){
+ yy = Y + rat*k/10.;
+ i = yy;
+ if(i < 0)
+ i = 0;
+ if(i >= iny)
+ i = iny-1;
+ v += in[i][off] * K[K2+k];
+ }
+ out[y][off] = v;
+ }
+
+}
+
+int
+max(int a, int b)
+{
+ if(a > b)
+ return a;
+ return b;
+}
+
+Memimage*
+resample(int xsize, int ysize, Memimage *m)
+{
+ int i, j, bpl, nchan;
+ Memimage *new;
+ uchar **oscan, **nscan;
+
+ new = allocmemimage(Rect(0, 0, xsize, ysize), m->chan);
+ if(new == nil)
+ sysfatal("can't allocate new image: %r");
+
+ oscan = malloc(Dy(m->r)*sizeof(uchar*));
+ nscan = malloc(max(ysize, Dy(m->r))*sizeof(uchar*));
+ if(oscan == nil || nscan == nil)
+ sysfatal("can't allocate: %r");
+
+ /* unload original image into scan lines */
+ bpl = bytesperline(m->r, m->depth);
+ for(i=0; i<Dy(m->r); i++){
+ oscan[i] = malloc(bpl);
+ if(oscan[i] == nil)
+ sysfatal("can't allocate: %r");
+ j = unloadmemimage(m, Rect(m->r.min.x, m->r.min.y+i, m->r.max.x, m->r.min.y+i+1), oscan[i], bpl);
+ if(j != bpl)
+ sysfatal("unloadmemimage");
+ }
+
+ /* allocate scan lines for destination. we do y first, so need at least Dy(m->r) lines */
+ bpl = bytesperline(Rect(0, 0, xsize, Dy(m->r)), m->depth);
+ for(i=0; i<max(ysize, Dy(m->r)); i++){
+ nscan[i] = malloc(bpl);
+ if(nscan[i] == nil)
+ sysfatal("can't allocate: %r");
+ }
+
+ /* resample in X */
+ nchan = m->depth/8;
+ for(i=0; i<Dy(m->r); i++){
+ for(j=0; j<nchan; j++){
+ if(j==0 && m->chan==XRGB32)
+ continue;
+ resamplex(oscan[i], j, nchan, Dx(m->r), nscan[i], xsize);
+ }
+ free(oscan[i]);
+ oscan[i] = nscan[i];
+ nscan[i] = malloc(bpl);
+ if(nscan[i] == nil)
+ sysfatal("can't allocate: %r");
+ }
+
+ /* resample in Y */
+ for(i=0; i<xsize; i++)
+ for(j=0; j<nchan; j++)
+ resampley(oscan, nchan*i+j, Dy(m->r), nscan, ysize);
+
+ /* pack data into destination */
+ bpl = bytesperline(new->r, m->depth);
+ for(i=0; i<ysize; i++){
+ j = loadmemimage(new, Rect(0, i, xsize, i+1), nscan[i], bpl);
+ if(j != bpl)
+ sysfatal("loadmemimage: %r");
+ }
+ return new;
+}
+
+void
+main(int argc, char *argv[])
+{
+ int i, fd, xsize, ysize, xpercent, ypercent;
+ Rectangle rparam;
+ Memimage *m, *new, *t1, *t2;
+ char *file;
+ ulong tchan;
+ char tmp[100];
+ double v;
+
+ for(i=-K2; i<=K2; i++){
+ K[K2+i] = kaiser(i/10., K2/10., 4.);
+// print("%g %g\n", i/10., K[K2+i]);
+ }
+
+ /* normalize */
+ v = 0.0;
+ for(i=0; i<NK; i++)
+ v += K[i];
+ for(i=0; i<NK; i++)
+ K[i] /= v;
+
+ memimageinit();
+ memset(&rparam, 0, sizeof rparam);
+ xsize = ysize = 0;
+ xpercent = ypercent = 0;
+
+ ARGBEGIN{
+ case 'a': /* compatibility; equivalent to just -x or -y */
+ if(xsize != 0 || ysize != 0)
+ usage();
+ xsize = getint(ARGF(), &xpercent);
+ if(xsize <= 0)
+ usage();
+ ysize = xsize;
+ ypercent = xpercent;
+ break;
+ case 'x':
+ if(xsize != 0)
+ usage();
+ xsize = getint(ARGF(), &xpercent);
+ if(xsize <= 0)
+ usage();
+ break;
+ case 'y':
+ if(ysize != 0)
+ usage();
+ ysize = getint(ARGF(), &ypercent);
+ if(ysize <= 0)
+ usage();
+ break;
+ default:
+ usage();
+ }ARGEND
+
+ if(xsize == 0 && ysize == 0)
+ usage();
+
+ file = "<stdin>";
+ fd = 0;
+ if(argc > 1)
+ usage();
+ else if(argc == 1){
+ file = argv[0];
+ fd = open(file, OREAD);
+ if(fd < 0)
+ sysfatal("can't open %s: %r", file);
+ }
+
+ m = readmemimage(fd);
+ if(m == nil)
+ sysfatal("can't read %s: %r", file);
+
+ if(xpercent)
+ xsize = Dx(m->r)*xsize/100;
+ if(ypercent)
+ ysize = Dy(m->r)*ysize/100;
+ if(ysize == 0)
+ ysize = (xsize * Dy(m->r)) / Dx(m->r);
+ if(xsize == 0)
+ xsize = (ysize * Dx(m->r)) / Dy(m->r);
+
+ new = nil;
+ switch(m->chan){
+
+ case GREY8:
+ case RGB24:
+ case RGBA32:
+ case ARGB32:
+ case XRGB32:
+ new = resample(xsize, ysize, m);
+ break;
+
+ case CMAP8:
+ case RGB15:
+ case RGB16:
+ tchan = RGB24;
+ goto Convert;
+
+ case GREY1:
+ case GREY2:
+ case GREY4:
+ tchan = GREY8;
+ Convert:
+ /* use library to convert to byte-per-chan form, then convert back */
+ t1 = allocmemimage(m->r, tchan);
+ if(t1 == nil)
+ sysfatal("can't allocate temporary image: %r");
+ memimagedraw(t1, t1->r, m, m->r.min, nil, ZP, S);
+ t2 = resample(xsize, ysize, t1);
+ freememimage(t1);
+ new = allocmemimage(Rect(0, 0, xsize, ysize), m->chan);
+ if(new == nil)
+ sysfatal("can't allocate new image: %r");
+ /* should do error diffusion here */
+ memimagedraw(new, new->r, t2, t2->r.min, nil, ZP, S);
+ freememimage(t2);
+ break;
+
+ default:
+ sysfatal("can't handle channel type %s", chantostr(tmp, m->chan));
+ }
+
+ assert(new);
+ if(writememimage(1, new) < 0)
+ sysfatal("write error on output: %r");
+
+ exits(nil);
+}