From 9c2b4088f2f72806dfd05136845e8e11a2dfb7f8 Mon Sep 17 00:00:00 2001
From: "sgunderson@bigfoot.com" <>
Date: Sun, 3 Feb 2008 17:10:59 +0100
Subject: [PATCH] Invert horizontal and vertical order.

---
 qscale.c | 65 +++++++++++++++++++++++++++-----------------------------
 1 file changed, 31 insertions(+), 34 deletions(-)

diff --git a/qscale.c b/qscale.c
index 61f49c4..042d341 100644
--- a/qscale.c
+++ b/qscale.c
@@ -52,7 +52,7 @@ struct pix_desc {
 	unsigned startcoeff;
 };
 
-void hscale(unsigned char *pix, float *npix, unsigned w, unsigned h, unsigned nw)
+void hscale(float *pix, unsigned char *npix, unsigned w, unsigned h, unsigned nw)
 {
 	struct pix_desc *pd = (struct pix_desc *)malloc(nw * sizeof(struct pix_desc));
 	int size_coeffs = 8;
@@ -60,7 +60,7 @@ void hscale(unsigned char *pix, float *npix, unsigned w, unsigned h, unsigned nw
 	int num_coeffs = 0;
 	int x, y, sx;
 	double sf = (double)w / (double)nw;
-	double support = 3.0 * sf;
+	double support = (w > nw) ? (3.0 * sf) : (3.0 / sf);
 
 	/* calculate the filter */
 	for (x = 0; x < nw; ++x) {
@@ -80,13 +80,13 @@ void hscale(unsigned char *pix, float *npix, unsigned w, unsigned h, unsigned nw
 		pd[x].startcoeff = num_coeffs;
 
 		for (sx = start; sx <= end; ++sx) {
-			double nd = sx/sf - x;
+			double nd = (w > nw) ? (sx/sf - x) : (sx - x*sf);
 			double f = lanczos_tap(nd);
 			if (num_coeffs == size_coeffs) {
 				size_coeffs <<= 1;
 				coeffs = (float *)realloc(coeffs, size_coeffs * sizeof(float));
 			}
-			
+		
 			coeffs[num_coeffs++] = f;
 			sum += f;
 		}
@@ -97,22 +97,30 @@ void hscale(unsigned char *pix, float *npix, unsigned w, unsigned h, unsigned nw
 	}
 	
 	for (y = 0; y < h; ++y) {
-		unsigned char *sptr = pix + y*w;
-		float *dptr = npix + y*nw;
+		float *sptr = pix + y*w;
+		unsigned char *dptr = npix + y*nw;
 		for (x = 0; x < nw; ++x) {
 			float acc = 0.0;
 			float *cf = &coeffs[pd[x].startcoeff];
 			unsigned sx;
+			unsigned char ch;
 			
 			for (sx = pd[x].start; sx <= pd[x].end; ++sx) {
 				acc += sptr[sx] * *cf++;
 			}
-			*dptr++ = acc;
+
+			if (acc < 0.0)
+				ch = 0;
+			else if (acc > 255.0)
+				ch = 255;
+			else
+				ch = (unsigned char)acc;
+			*dptr++ = ch;
 		}
 	}
 }
 
-void vscale(float *pix, unsigned char *npix, unsigned w, unsigned h, unsigned nh)
+void vscale(unsigned char *pix, float *npix, unsigned w, unsigned h, unsigned nh)
 {
 	struct pix_desc *pd = (struct pix_desc *)malloc(nh * sizeof(struct pix_desc));
 	int size_coeffs = 8;
@@ -120,7 +128,7 @@ void vscale(float *pix, unsigned char *npix, unsigned w, unsigned h, unsigned nh
 	int num_coeffs = 0;
 	int x, y, sy;
 	double sf = (double)h / (double)nh;
-	double support = 3.0 * sf;
+	double support = (h > nh) ? (3.0 * sf) : (3.0 / sf);
 
 	/* calculate the filter */
 	for (y = 0; y < nh; ++y) {
@@ -140,7 +148,7 @@ void vscale(float *pix, unsigned char *npix, unsigned w, unsigned h, unsigned nh
 		pd[y].startcoeff = num_coeffs;
 
 		for (sy = start; sy <= end; ++sy) {
-			double nd = sy/sf - y;
+			double nd = (h > nh) ? (sy/sf - y) : (sy - y*sf);
 			double f = lanczos_tap(nd);
 			if (num_coeffs == size_coeffs) {
 				size_coeffs <<= 1;
@@ -155,10 +163,11 @@ void vscale(float *pix, unsigned char *npix, unsigned w, unsigned h, unsigned nh
 			coeffs[pd[y].startcoeff + sy - start] /= sum;
 		}
 	}
+
 #if CACHE_LINE_FACTOR > 1
 	for (x = 0; x < w; x += CACHE_LINE_FACTOR) {
-		float *sptr = pix + x;
-		unsigned char *dptr = npix + x;
+		unsigned char *sptr = pix + x;
+		float *dptr = npix + x;
 		for (y = 0; y < nh; ++y) {
 			int i;
 			float acc[CACHE_LINE_FACTOR];
@@ -166,7 +175,6 @@ void vscale(float *pix, unsigned char *npix, unsigned w, unsigned h, unsigned nh
 				acc[i] = 0.0;
 			float *cf = &coeffs[pd[y].startcoeff];
 			unsigned sy;
-			unsigned char ch;
 			
 			for (sy = pd[y].start; sy <= pd[y].end; ++sy) {
 				for (i = 0; i < CACHE_LINE_FACTOR; ++i) {
@@ -176,39 +184,27 @@ void vscale(float *pix, unsigned char *npix, unsigned w, unsigned h, unsigned nh
 			}
 
 			for (i = 0; i < CACHE_LINE_FACTOR; ++i) {
-				if (acc[i] < 0.0)
-					ch = 0;
-				else if (acc[i] > 255.0)
-					ch = 255;
-				else
-					ch = (unsigned char)acc[i];
-				dptr[i] = ch;
+				dptr[i] = acc[i];
 			}
 			dptr += w;
 		}
 	}
-#endif
 	for (x = (x/CACHE_LINE_FACTOR)*CACHE_LINE_FACTOR; x < w; ++x) {
-		float *sptr = pix + x;
-		unsigned char *dptr = npix + x;
+#else
+	for (x = 0; x < w; ++x) {
+#endif
+		unsigned char *sptr = pix + x;
+		float *dptr = npix + x;
 		for (y = 0; y < nh; ++y) {
 			float acc = 0.0;
 			float *cf = &coeffs[pd[y].startcoeff];
 			unsigned sy;
-			unsigned char ch;
 			
 			for (sy = pd[y].start; sy <= pd[y].end; ++sy) {
 				acc += sptr[sy * w] * *cf++;
 			}
 
-			if (acc < 0.0)
-				ch = 0;
-			else if (acc > 255.0)
-				ch = 255;
-			else
-				ch = (unsigned char)acc;
-
-			*dptr = ch;
+			*dptr = acc;
 			dptr += w;
 		}
 	}
@@ -218,6 +214,7 @@ int main(void)
 {
 	unsigned w, h;
 	unsigned nw = 600, nh = 400;
+	//unsigned nw = 3504, nh = 2336;
 	char buf[256];
 	unsigned char *pix;
 	float *npix;
@@ -264,8 +261,8 @@ int main(void)
 		exit(1);
 	}
 
-	hscale(pix, npix, w, h, nw);
-	vscale(npix, npix2, nw, h, nh);
+	vscale(pix, npix, w, h, nh);
+	hscale(npix, npix2, w, nh, nw);
 
 	printf("P5\n# COMMENT: Made by qscale\n%u %u\n255\n", nw, nh);
 	{
-- 
2.39.2