This is patch [#6929] Interpolation Methods

http://projects.blender.org/tracker/index.php?func=detail&aid=6929&group_id=9&atid=127
Its a subset of patch [#6766] Transform Sequencer effect

It adds 3 image functions for different types of interpolation.
For people that like pictures:
http://wiki.blender.org/index.php/User:Damiles#Interpolations_Algorithms

Patch provided by David Millán Escrivá (damiles)

Kent

2 files changed, 234 insertions, 1 deletions

diff --git a/source/blender/imbuf/IMB_imbuf.h b/source/blender/imbuf/IMB_imbuf.h
index d6ca21830aa..840d39ea0bd 100644
--- a/source/blender/imbuf/IMB_imbuf.h
+++ b/source/blender/imbuf/IMB_imbuf.h
@@ -395,7 +395,13 @@ void IMB_float_from_rect(struct ImBuf *ibuf);
  * @attention Defined in imageprocess.c
  */
 void IMB_convert_rgba_to_abgr(struct ImBuf *ibuf);
-
+/**
+ *
+ * @attention defined in imageprocess.c
+ */
+void bicubic_interpolation(struct ImBuf *in, struct ImBuf *out, float x, float y, int xout, int yout);
+void neareast_interpolation(struct ImBuf *in, struct ImBuf *out, float u, float v, int xout, int yout);
+void bilinear_interpolation(struct ImBuf *in, struct ImBuf *out, float u, float v, int xout, int yout);
 /**
  * Change the ordering of the color bytes pointed to by rect from
  * rgba to abgr. size * 4 color bytes are reordered.
diff --git a/source/blender/imbuf/intern/imageprocess.c b/source/blender/imbuf/intern/imageprocess.c
index f98244c5a0f..855c80c820d 100644
--- a/source/blender/imbuf/intern/imageprocess.c
+++ b/source/blender/imbuf/intern/imageprocess.c
@@ -42,6 +42,11 @@
 
 #include "IMB_imbuf_types.h"
 #include "IMB_imbuf.h"
+#include "math.h"
+
+/* This define should be relocated to a global header some where  Kent Mein 
+I stole it from util.h in the plugins api */
+#define MAX2(x,y)                ( (x)>(y) ? (x) : (y) )
 
 /* Only this one is used liberally here, and in imbuf */
 void IMB_convert_rgba_to_abgr(struct ImBuf *ibuf)
@@ -73,3 +78,225 @@ void IMB_convert_rgba_to_abgr(struct ImBuf *ibuf)
 	}
 }
 
+/**************************************************************************
+*                            INTERPOLATIONS 
+*
+* Reference and docs:
+* http://wiki.blender.org/index.php/User:Damiles#Interpolations_Algorithms
+***************************************************************************/
+
+/* BICUBIC */
+
+/* Bicubic formula:
+*
+*  A’(px,py) = Σn=-1..2Σm=-1..2 A(i+n,j+m)·P(n-a)·P(b-m)
+*  with: P(k) = 1/6(C(k+2)^3-4C(k+1)^3+6C(k)^3-4C(k-1)^3)
+*  and C(k) = max(0, k)
+*
+*  Where A= in and A'=out
+*
+*  More info: http://wiki.blender.org/index.php/User:Damiles#Bicubic_pixel_interpolation
+*/
+/* function assumes out to be zero'ed, only does RGBA */
+static float P(float k){
+	float aux;
+	aux=(float)(1.0f/6.0f)*( pow( MAX2(k+2.0f,0) , 3.0f ) - 4.0f * pow( MAX2(k+1.0f,0) , 3.0f ) + 6.0f * pow( MAX2(k,0) , 3.0f ) - 4.0f * pow( MAX2(k-1.0f,0) , 3.0f));
+	return aux ;
+}
+
+void bicubic_interpolation(ImBuf *in, ImBuf *out, float x, float y, int xout, int yout)
+{
+	int i,j,n,m,x1,y1;
+	unsigned char *dataI,*outI;
+	float a,b, outR,outG,outB,outA,*dataF,*outF;
+	int do_rect, do_float;
+
+	if (in == NULL) return;
+	if (in->rect == NULL && in->rect_float == NULL) return;
+
+	do_rect= (in->rect != NULL);
+	do_float= (in->rect_float != NULL);
+
+	i= (int)floor(x);
+	j= (int)floor(y);
+	a= x - i;
+	b= y - j;
+
+	outR= 0.0f;
+	outG= 0.0f;
+	outB= 0.0f;
+	outA= 0.0f;
+	for(n= -1; n<= 2; n++){
+		for(m= -1; m<= 2; m++){
+			x1= i+n;
+			y1= j+m;
+			if (x1>0 && x1 < in->x && y1>0 && y1<in->y) {
+				if (do_float) {
+					dataF= in->rect_float + in->x * y1 * 4 + 4*x1;
+					outR+= dataF[0] * P(n-a) * P(b-m);
+					outG+= dataF[1] * P(n-a) * P(b-m);
+					outB+= dataF[2] * P(n-a) * P(b-m);
+					outA+= dataF[3] * P(n-a) * P(b-m);
+				}
+				if (do_rect) {
+					dataI= (unsigned char*)in->rect + in->x * y1 * 4 + 4*x1;
+					outR+= dataI[0] * P(n-a) * P(b-m);
+					outG+= dataI[1] * P(n-a) * P(b-m);
+					outB+= dataI[2] * P(n-a) * P(b-m);
+					outA+= dataI[3] * P(n-a) * P(b-m);
+				}
+			}
+		}
+	}
+	if (do_rect) {
+		outI= (unsigned char *)out->rect + out->x * yout * 4 + 4*xout;
+		outI[0]= (int)outR;
+		outI[1]= (int)outG;
+		outI[2]= (int)outB;
+		outI[3]= (int)outA;
+	}
+	if (do_float) {
+		outF= (float *)out->rect_float + out->x * yout * 4 + 4*xout;
+		outF[0]= outR;
+		outF[1]= outG;
+		outF[2]= outB;
+		outF[3]= outA;
+	}
+}
+
+/* function assumes out to be zero'ed, only does RGBA */
+/* BILINEAR INTERPOLATION */
+void bilinear_interpolation(ImBuf *in, ImBuf *out, float u, float v, int xout, int yout)
+{
+	float *row1, *row2, *row3, *row4, a, b, *outF;
+	unsigned char *row1I, *row2I, *row3I, *row4I, *outI;
+	float a_b, ma_b, a_mb, ma_mb;
+	float empty[4]= {0.0f, 0.0f, 0.0f, 0.0f};
+	unsigned char emptyI[4]= {0, 0, 0, 0};
+	int y1, y2, x1, x2;
+	int do_rect, do_float;
+
+	if (in==NULL) return;
+	if (in->rect==NULL && in->rect_float==NULL) return;
+
+	do_rect= (in->rect != NULL);
+	do_float= (in->rect_float != NULL);
+
+	x1= (int)floor(u);
+	x2= (int)ceil(u);
+	y1= (int)floor(v);
+	y2= (int)ceil(v);
+
+	// sample area entirely outside image? 
+	if (x2<0 || x1>in->x-1 || y2<0 || y1>in->y-1) return;
+
+	if (do_rect)
+		outI=(unsigned char *)out->rect + out->x * yout * 4 + 4*xout;
+	if (do_float)
+		outF=(float *)out->rect_float + out->x * yout * 4 + 4*xout;
+
+	if (do_float) {
+		// sample including outside of edges of image 
+		if (x1<0 || y1<0) row1= empty;
+		else row1= (float *)in->rect_float + in->x * y1 * 4 + 4*x1;
+		
+		if (x1<0 || y2>in->y-1) row2= empty;
+		else row2= (float *)in->rect_float + in->x * y2 * 4 + 4*x1;
+		
+		if (x2>in->x-1 || y1<0) row3= empty;
+		else row3= (float *)in->rect_float + in->x * y1 * 4 + 4*x2;
+		
+		if (x2>in->x-1 || y2>in->y-1) row4= empty;
+		else row4= (float *)in->rect_float + in->x * y2 * 4 + 4*x2;
+		
+		a= u-floor(u);
+		b= v-floor(v);
+		a_b= a*b; ma_b= (1.0f-a)*b; a_mb= a*(1.0f-b); ma_mb= (1.0f-a)*(1.0f-b);
+		
+		outF[0]= ma_mb*row1[0] + a_mb*row3[0] + ma_b*row2[0]+ a_b*row4[0];
+		outF[1]= ma_mb*row1[1] + a_mb*row3[1] + ma_b*row2[1]+ a_b*row4[1];
+		outF[2]= ma_mb*row1[2] + a_mb*row3[2] + ma_b*row2[2]+ a_b*row4[2];
+		outF[3]= ma_mb*row1[3] + a_mb*row3[3] + ma_b*row2[3]+ a_b*row4[3];
+	}
+	if (do_rect) {
+		// sample including outside of edges of image 
+		if (x1<0 || y1<0) row1I= emptyI;
+		else row1I= (unsigned char *)in->rect + in->x * y1 * 4 + 4*x1;
+		
+		if (x1<0 || y2>in->y-1) row2I= emptyI;
+		else row2I= (unsigned char *)in->rect + in->x * y2 * 4 + 4*x1;
+		
+		if (x2>in->x-1 || y1<0) row3I= emptyI;
+		else row3I= (unsigned char *)in->rect + in->x * y1 * 4 + 4*x2;
+		
+		if (x2>in->x-1 || y2>in->y-1) row4I= emptyI;
+		else row4I= (unsigned char *)in->rect + in->x * y2 * 4 + 4*x2;
+		
+		a= u-floor(u);
+		b= v-floor(v);
+		a_b= a*b; ma_b= (1.0f-a)*b; a_mb= a*(1.0f-b); ma_mb= (1.0f-a)*(1.0f-b);
+		
+		outI[0]= ma_mb*row1I[0] + a_mb*row3I[0] + ma_b*row2I[0]+ a_b*row4I[0];
+		outI[1]= ma_mb*row1I[1] + a_mb*row3I[1] + ma_b*row2I[1]+ a_b*row4I[1];
+		outI[2]= ma_mb*row1I[2] + a_mb*row3I[2] + ma_b*row2I[2]+ a_b*row4I[2];
+		outI[3]= ma_mb*row1I[3] + a_mb*row3I[3] + ma_b*row2I[3]+ a_b*row4I[3];
+	}
+}
+
+/* function assumes out to be zero'ed, only does RGBA */
+/* NEAREST INTERPOLATION */
+void neareast_interpolation(ImBuf *in, ImBuf *out, float u, float v,int xout, int yout)
+{
+	float *outF,*dataF;
+	unsigned char *dataI,*outI;
+	int y1, x1;
+	int do_rect, do_float;
+
+	if (in==NULL) return;
+	if (in->rect==NULL && in->rect_float==NULL) return;
+
+	do_rect= (in->rect != NULL);
+	do_float= (in->rect_float != NULL);
+
+	x1= (int)(u);
+	y1= (int)(v);
+
+	if (do_rect)
+		outI=(unsigned char *)out->rect + out->x * yout * 4 + 4*xout;
+	if (do_float)
+		outF=(float *)out->rect_float + out->x * yout * 4 + 4*xout;
+
+	// sample area entirely outside image? 
+	if (x1<0 || x1>in->x-1 || y1<0 || y1>in->y-1) return;
+	
+	// sample including outside of edges of image 
+	if (x1<0 || y1<0) {
+		if (do_rect) {
+			outI[0]= 0;
+			outI[1]= 0;
+			outI[2]= 0;
+			outI[3]= 0;
+		}
+		if (do_float) {
+			outF[0]= 0.0f;
+			outF[1]= 0.0f;
+			outF[2]= 0.0f;
+			outF[3]= 0.0f;
+		}
+	} else {
+		dataI= (unsigned char *)in->rect + in->x * y1 * 4 + 4*x1;
+		if (do_rect) {
+			outI[0]= dataI[0];
+			outI[1]= dataI[1];
+			outI[2]= dataI[2];
+			outI[3]= dataI[3];
+		}
+		dataF= in->rect_float + in->x * y1 * 4 + 4*x1;
+		if (do_float) {
+			outF[0]= dataF[0];
+			outF[1]= dataF[1];
+			outF[2]= dataF[2];
+			outF[3]= dataF[3];
+		}
+	}	
+}