Code de-duplication in imageprocess.c -- made it use interpolation functions from blenlib

4 files changed, 195 insertions, 249 deletions

diff --git a/source/blender/blenlib/BLI_math_interp.h b/source/blender/blenlib/BLI_math_interp.h
index 3a107be32bd..21975763779 100644
--- a/source/blender/blenlib/BLI_math_interp.h
+++ b/source/blender/blenlib/BLI_math_interp.h
@@ -29,7 +29,16 @@
 #ifndef BLI_MATH_INTERP
 #define BLI_MATH_INTERP
 
-void BLI_bicubic_interpolation(const float *buffer, float *output, int width, int height, int components, float u, float v);
-void BLI_bilinear_interpolation(const float *buffer, float *output, int width, int height, int components, float u, float v);
+void BLI_bicubic_interpolation_fl(const float *buffer, float *output, int width, int height,
+                                  int components, float u, float v);
+
+void BLI_bicubic_interpolation_char(const unsigned char *buffer, unsigned char *output, int width, int height,
+                                    int components, float u, float v);
+
+void BLI_bilinear_interpolation_fl(const float *buffer, float *output, int width, int height,
+                                   int components, float u, float v);
+
+void BLI_bilinear_interpolation_char(const unsigned char *buffer, unsigned char *output, int width, int height,
+                                     int components, float u, float v);
 
 #endif
diff --git a/source/blender/blenlib/intern/math_interp.c b/source/blender/blenlib/intern/math_interp.c
index 742669354a9..59a1c1f649c 100644
--- a/source/blender/blenlib/intern/math_interp.c
+++ b/source/blender/blenlib/intern/math_interp.c
@@ -60,12 +60,44 @@ static float P(float k)
 }
 #endif
 
+static void vector_from_float(const float *data, float vector[4], int components)
+{
+	if (components == 1) {
+		vector[0] = data[0];
+	}
+	else if (components == 3) {
+		copy_v3_v3(vector, data);
+	}
+	else {
+		copy_v4_v4(vector, data);
+	}
+}
+
+static void vector_from_byte(const unsigned char *data, float vector[4], int components)
+{
+	if (components == 1) {
+		vector[0] = data[0];
+	}
+	else if (components == 3) {
+		vector[0] = data[0];
+		vector[1] = data[1];
+		vector[2] = data[2];
+	}
+	else {
+		vector[0] = data[0];
+		vector[1] = data[1];
+		vector[2] = data[2];
+		vector[3] = data[3];
+	}
+}
+
 /* BICUBIC INTERPOLATION */
-void BLI_bicubic_interpolation(const float *buffer, float *output, int width, int height, int components, float u, float v)
+BLI_INLINE void bicubic_interpolation(const unsigned char *byte_buffer, const float *float_buffer,
+                                      unsigned char *byte_output, float *float_output, int width, int height,
+                                      int components, float u, float v)
 {
 	int i, j, n, m, x1, y1;
 	float a, b, w, wx, wy[4], out[4];
-	const float *data;
 
 	/* sample area entirely outside image? */
 	if (ceil(u) < 0 || floor(u) > width - 1 || ceil(v) < 0 || floor(v) > height - 1) {
@@ -92,6 +124,8 @@ void BLI_bicubic_interpolation(const float *buffer, float *output, int width, in
 		CLAMP(x1, 0, width - 1);
 		wx = P(n - a);
 		for (m = -1; m <= 2; m++) {
+			float data[4];
+
 			y1 = j + m;
 			CLAMP(y1, 0, height - 1);
 			/* normally we could do this */
@@ -99,14 +133,19 @@ void BLI_bicubic_interpolation(const float *buffer, float *output, int width, in
 			/* except that would call P() 16 times per pixel therefor pow() 64 times, better precalc these */
 			w = wx * wy[m + 1];
 
-			data = buffer + width * y1 * 4 + 4 * x1;
+			if (float_output) {
+				const float *float_data = float_buffer + width * y1 * 4 + 4 * x1;
 
-			if (components == 1) {
-				out[0] += data[0] * w;
+				vector_from_float(float_data, data, components);
+			}
+			else {
+				const unsigned char *byte_data = byte_buffer + width * y1 * 4 + 4 * x1;
+
+				vector_from_byte(byte_data, data, components);
 			}
-			else if (components == 2) {
+
+			if (components == 1) {
 				out[0] += data[0] * w;
-				out[1] += data[1] * w;
 			}
 			else if (components == 3) {
 				out[0] += data[0] * w;
@@ -131,14 +170,21 @@ void BLI_bicubic_interpolation(const float *buffer, float *output, int width, in
 			x1 = i + n;
 			y1 = j + m;
 			if (x1 > 0 && x1 < width && y1 > 0 && y1 < height) {
-				data = in->rect_float + width * y1 * 4 + 4 * x1;
+				float data[4];
 
-				if (components == 1) {
-					out[0] += data[0] * P(n - a) * P(b - m);
+				if (float_output) {
+					const float *float_data = float_buffer + width * y1 * 4 + 4 * x1;
+
+					vector_from_float(float_data, data, components);
 				}
-				else if (components == 2) {
+				else {
+					const unsigned char *byte_data = byte_buffer + width * y1 * 4 + 4 * x1;
+
+					vector_from_byte(byte_data, data, components);
+				}
+
+				if (components == 1) {
 					out[0] += data[0] * P(n - a) * P(b - m);
-					out[1] += data[1] * P(n - a) * P(b - m);
 				}
 				else if (components == 3) {
 					out[0] += data[0] * P(n - a) * P(b - m);
@@ -156,33 +202,54 @@ void BLI_bicubic_interpolation(const float *buffer, float *output, int width, in
 	}
 #endif
 
-	if (components == 1) {
-		output[0] = out[0];
-	}
-	else if (components == 2) {
-		output[0] = out[0];
-		output[1] = out[1];
-	}
-	else if (components == 3) {
-		output[0] = out[0];
-		output[1] = out[1];
-		output[2] = out[2];
+	if (float_output) {
+		if (components == 1) {
+			float_output[0] = out[0];
+		}
+		else if (components == 3) {
+			copy_v3_v3(float_output, out);
+		}
+		else {
+			copy_v4_v4(float_output, out);
+		}
 	}
 	else {
-		output[0] = out[0];
-		output[1] = out[1];
-		output[2] = out[2];
-		output[3] = out[3];
+		if (components == 1) {
+			byte_output[0] = out[0];
+		}
+		else if (components == 3) {
+			byte_output[0] = out[0];
+			byte_output[1] = out[1];
+			byte_output[2] = out[2];
+		}
+		else {
+			byte_output[0] = out[0];
+			byte_output[1] = out[1];
+			byte_output[2] = out[2];
+			byte_output[3] = out[3];
+		}
 	}
 }
 
+void BLI_bicubic_interpolation_fl(const float *buffer, float *output, int width, int height,
+                                  int components, float u, float v)
+{
+	bicubic_interpolation(NULL, buffer, NULL, output, width, height, components, u, v);
+}
+
+void BLI_bicubic_interpolation_char(const unsigned char *buffer, unsigned char *output, int width, int height,
+                                    int components, float u, float v)
+{
+	bicubic_interpolation(buffer, NULL, output, NULL, width, height, components, u, v);
+}
+
 /* BILINEAR INTERPOLATION */
-void BLI_bilinear_interpolation(const float *buffer, float *output, int width, int height, int components, float u, float v)
+BLI_INLINE void bilinear_interpolation(const unsigned char *byte_buffer, const float *float_buffer,
+                                       unsigned char *byte_output, float *float_output, int width, int height,
+                                       int components, float u, float v)
 {
-	const float *row1, *row2, *row3, *row4;
 	float a, b;
 	float a_b, ma_b, a_mb, ma_mb;
-	float empty[4] = {0.0f, 0.0f, 0.0f, 0.0f};
 	int y1, y2, x1, x2;
 
 	/* ImBuf in must have a valid rect or rect_float, assume this is already checked */
@@ -197,39 +264,88 @@ void BLI_bilinear_interpolation(const float *buffer, float *output, int width, i
 		return;
 	}
 
-	/* sample including outside of edges of image */
-	if (x1 < 0 || y1 < 0) row1 = empty;
-	else row1 = buffer + width * y1 * 4 + 4 * x1;
+	if (float_output) {
+		const float *row1, *row2, *row3, *row4;
+		float empty[4] = {0.0f, 0.0f, 0.0f, 0.0f};
 
-	if (x1 < 0 || y2 > height - 1) row2 = empty;
-	else row2 = buffer + width * y2 * 4 + 4 * x1;
+		/* sample including outside of edges of image */
+		if (x1 < 0 || y1 < 0) row1 = empty;
+		else row1 = float_buffer + width * y1 * 4 + 4 * x1;
 
-	if (x2 > width - 1 || y1 < 0) row3 = empty;
-	else row3 = buffer + width * y1 * 4 + 4 * x2;
+		if (x1 < 0 || y2 > height - 1) row2 = empty;
+		else row2 = float_buffer + width * y2 * 4 + 4 * x1;
 
-	if (x2 > width - 1 || y2 > height - 1) row4 = empty;
-	else row4 = buffer + width * y2 * 4 + 4 * x2;
+		if (x2 > width - 1 || y1 < 0) row3 = empty;
+		else row3 = float_buffer + width * y1 * 4 + 4 * x2;
 
-	a = u - floorf(u);
-	b = v - floorf(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);
+		if (x2 > width - 1 || y2 > height - 1) row4 = empty;
+		else row4 = float_buffer + width * y2 * 4 + 4 * x2;
 
-	if (components == 1) {
-		output[0] = ma_mb * row1[0] + a_mb * row3[0] + ma_b * row2[0] + a_b * row4[0];
-	}
-	else if (components == 2) {
-		output[0] = ma_mb * row1[0] + a_mb * row3[0] + ma_b * row2[0] + a_b * row4[0];
-		output[1] = ma_mb * row1[1] + a_mb * row3[1] + ma_b * row2[1] + a_b * row4[1];
-	}
-	else if (components == 3) {
-		output[0] = ma_mb * row1[0] + a_mb * row3[0] + ma_b * row2[0] + a_b * row4[0];
-		output[1] = ma_mb * row1[1] + a_mb * row3[1] + ma_b * row2[1] + a_b * row4[1];
-		output[2] = ma_mb * row1[2] + a_mb * row3[2] + ma_b * row2[2] + a_b * row4[2];
+		a = u - floorf(u);
+		b = v - floorf(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);
+
+		if (components == 1) {
+			float_output[0] = ma_mb * row1[0] + a_mb * row3[0] + ma_b * row2[0] + a_b * row4[0];
+		}
+		else if (components == 3) {
+			float_output[0] = ma_mb * row1[0] + a_mb * row3[0] + ma_b * row2[0] + a_b * row4[0];
+			float_output[1] = ma_mb * row1[1] + a_mb * row3[1] + ma_b * row2[1] + a_b * row4[1];
+			float_output[2] = ma_mb * row1[2] + a_mb * row3[2] + ma_b * row2[2] + a_b * row4[2];
+		}
+		else {
+			float_output[0] = ma_mb * row1[0] + a_mb * row3[0] + ma_b * row2[0] + a_b * row4[0];
+			float_output[1] = ma_mb * row1[1] + a_mb * row3[1] + ma_b * row2[1] + a_b * row4[1];
+			float_output[2] = ma_mb * row1[2] + a_mb * row3[2] + ma_b * row2[2] + a_b * row4[2];
+			float_output[3] = ma_mb * row1[3] + a_mb * row3[3] + ma_b * row2[3] + a_b * row4[3];
+		}
 	}
 	else {
-		output[0] = ma_mb * row1[0] + a_mb * row3[0] + ma_b * row2[0] + a_b * row4[0];
-		output[1] = ma_mb * row1[1] + a_mb * row3[1] + ma_b * row2[1] + a_b * row4[1];
-		output[2] = ma_mb * row1[2] + a_mb * row3[2] + ma_b * row2[2] + a_b * row4[2];
-		output[3] = ma_mb * row1[3] + a_mb * row3[3] + ma_b * row2[3] + a_b * row4[3];
+		const unsigned char *row1, *row2, *row3, *row4;
+		unsigned char empty[4] = {0, 0, 0, 0};
+
+		/* sample including outside of edges of image */
+		if (x1 < 0 || y1 < 0) row1 = empty;
+		else row1 = byte_buffer + width * y1 * 4 + 4 * x1;
+
+		if (x1 < 0 || y2 > height - 1) row2 = empty;
+		else row2 = byte_buffer + width * y2 * 4 + 4 * x1;
+
+		if (x2 > width - 1 || y1 < 0) row3 = empty;
+		else row3 = byte_buffer + width * y1 * 4 + 4 * x2;
+
+		if (x2 > width - 1 || y2 > height - 1) row4 = empty;
+		else row4 = byte_buffer + width * y2 * 4 + 4 * x2;
+
+		a = u - floorf(u);
+		b = v - floorf(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);
+
+		if (components == 1) {
+			byte_output[0] = ma_mb * row1[0] + a_mb * row3[0] + ma_b * row2[0] + a_b * row4[0];
+		}
+		else if (components == 3) {
+			byte_output[0] = ma_mb * row1[0] + a_mb * row3[0] + ma_b * row2[0] + a_b * row4[0];
+			byte_output[1] = ma_mb * row1[1] + a_mb * row3[1] + ma_b * row2[1] + a_b * row4[1];
+			byte_output[2] = ma_mb * row1[2] + a_mb * row3[2] + ma_b * row2[2] + a_b * row4[2];
+		}
+		else {
+			byte_output[0] = ma_mb * row1[0] + a_mb * row3[0] + ma_b * row2[0] + a_b * row4[0];
+			byte_output[1] = ma_mb * row1[1] + a_mb * row3[1] + ma_b * row2[1] + a_b * row4[1];
+			byte_output[2] = ma_mb * row1[2] + a_mb * row3[2] + ma_b * row2[2] + a_b * row4[2];
+			byte_output[3] = ma_mb * row1[3] + a_mb * row3[3] + ma_b * row2[3] + a_b * row4[3];
+		}
 	}
 }
+
+void BLI_bilinear_interpolation_fl(const float *buffer, float *output, int width, int height,
+                                   int components, float u, float v)
+{
+	bilinear_interpolation(NULL, buffer, NULL, output, width, height, components, u, v);
+}
+
+void BLI_bilinear_interpolation_char(const unsigned char *buffer, unsigned char *output, int width, int height,
+                                     int components, float u, float v)
+{
+	bilinear_interpolation(buffer, NULL, output, NULL, width, height, components, u, v);
+}
diff --git a/source/blender/compositor/operations/COM_RenderLayersBaseProg.cpp b/source/blender/compositor/operations/COM_RenderLayersBaseProg.cpp
index f4160a5fbcb..2ca499683d3 100644
--- a/source/blender/compositor/operations/COM_RenderLayersBaseProg.cpp
+++ b/source/blender/compositor/operations/COM_RenderLayersBaseProg.cpp
@@ -91,11 +91,11 @@ void RenderLayersBaseProg::doInterpolation(float output[4], float x, float y, Pi
 			break;
 
 		case COM_PS_BILINEAR:
-			BLI_bilinear_interpolation(this->m_inputBuffer, output, width, height, this->m_elementsize, x, y);
+			BLI_bilinear_interpolation_fl(this->m_inputBuffer, output, width, height, this->m_elementsize, x, y);
 			break;
 
 		case COM_PS_BICUBIC:
-			BLI_bicubic_interpolation(this->m_inputBuffer, output, width, height, this->m_elementsize, x, y);
+			BLI_bicubic_interpolation_fl(this->m_inputBuffer, output, width, height, this->m_elementsize, x, y);
 			break;
 	}
 
diff --git a/source/blender/imbuf/intern/imageprocess.c b/source/blender/imbuf/intern/imageprocess.c
index 57fbce710a1..a185c4ee3e0 100644
--- a/source/blender/imbuf/intern/imageprocess.c
+++ b/source/blender/imbuf/intern/imageprocess.c
@@ -43,6 +43,7 @@
 #include "BLI_utildefines.h"
 #include "BLI_threads.h"
 #include "BLI_listbase.h"
+#include "BLI_math.h"
 
 #include "IMB_imbuf_types.h"
 #include "IMB_imbuf.h"
@@ -95,132 +96,15 @@ static void pixel_from_buffer(struct ImBuf *ibuf, unsigned char **outI, float **
 		*outF = ibuf->rect_float + offset;
 }
 
-/**************************************************************************
- *                            INTERPOLATIONS
- *
- * Reference and docs:
- * http://wiki.blender.org/index.php/User:Damiles#Interpolations_Algorithms
- ***************************************************************************/
-
-/* BICUBIC Interpolation functions
- *  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 p1, p2, p3, p4;
-	p1 = MAX2(k + 2.0f, 0);
-	p2 = MAX2(k + 1.0f, 0);
-	p3 = MAX2(k, 0);
-	p4 = MAX2(k - 1.0f, 0);
-	return (float)(1.0f / 6.0f) * (p1 * p1 * p1 - 4.0f * p2 * p2 * p2 + 6.0f * p3 * p3 * p3 - 4.0f * p4 * p4 * p4);
-}
-
-
-#if 0
-/* older, slower function, works the same as above */
-static float P(float k)
-{
-	return (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));
-}
-#endif
+/* BICUBIC Interpolation */
 
 void bicubic_interpolation_color(struct ImBuf *in, unsigned char outI[4], float outF[4], float u, float v)
 {
-	int i, j, n, m, x1, y1;
-	unsigned char *dataI;
-	float a, b, w, wx, wy[4], outR, outG, outB, outA, *dataF;
-
-	/* sample area entirely outside image? */
-	if (ceil(u) < 0 || floor(u) > in->x - 1 || ceil(v) < 0 || floor(v) > in->y - 1) {
-		return;
-	}
-
-	/* ImBuf in must have a valid rect or rect_float, assume this is already checked */
-
-	i = (int)floor(u);
-	j = (int)floor(v);
-	a = u - i;
-	b = v - j;
-
-	outR = outG = outB = outA = 0.0f;
-	
-/* Optimized and not so easy to read */
-	
-	/* avoid calling multiple times */
-	wy[0] = P(b - (-1));
-	wy[1] = P(b -  0);
-	wy[2] = P(b -  1);
-	wy[3] = P(b -  2);
-
-	for (n = -1; n <= 2; n++) {
-		x1 = i + n;
-		CLAMP(x1, 0, in->x - 1);
-		wx = P(n - a);
-		for (m = -1; m <= 2; m++) {
-			y1 = j + m;
-			CLAMP(y1, 0, in->y - 1);
-			/* normally we could do this */
-			/* w = P(n-a) * P(b-m); */
-			/* except that would call P() 16 times per pixel therefor pow() 64 times, better precalc these */
-			w = wx * wy[m + 1];
-
-			if (outF) {
-				dataF = in->rect_float + in->x * y1 * 4 + 4 * x1;
-				outR += dataF[0] * w;
-				outG += dataF[1] * w;
-				outB += dataF[2] * w;
-				outA += dataF[3] * w;
-			}
-			if (outI) {
-				dataI = (unsigned char *)in->rect + in->x * y1 * 4 + 4 * x1;
-				outR += dataI[0] * w;
-				outG += dataI[1] * w;
-				outB += dataI[2] * w;
-				outA += dataI[3] * w;
-			}
-		}
-	}
-
-/* Done with optimized part */
-	
-#if 0 
-	/* older, slower function, works the same as above */
-	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);
-				}
-			}
-		}
-	}
-#endif
-	
-	if (outI) {
-		outI[0] = (int)outR;
-		outI[1] = (int)outG;
-		outI[2] = (int)outB;
-		outI[3] = (int)outA;
-	}
 	if (outF) {
-		outF[0] = outR;
-		outF[1] = outG;
-		outF[2] = outB;
-		outF[3] = outA;
+		BLI_bicubic_interpolation_fl(in->rect_float, outF, in->x, in->y, 4, u, v);
+	}
+	else {
+		BLI_bicubic_interpolation_char((unsigned char*) in->rect, outI, in->x, in->y, 4, u, v);
 	}
 }
 
@@ -239,77 +123,14 @@ void bicubic_interpolation(ImBuf *in, ImBuf *out, float u, float v, int xout, in
 	bicubic_interpolation_color(in, outI, outF, u, v);
 }
 
-/* function assumes out to be zero'ed, only does RGBA */
 /* BILINEAR INTERPOLATION */
 void bilinear_interpolation_color(struct ImBuf *in, unsigned char outI[4], float outF[4], float u, float v)
 {
-	float *row1, *row2, *row3, *row4, a, b;
-	unsigned char *row1I, *row2I, *row3I, *row4I;
-	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;
-	
-	
-	/* ImBuf in must have a valid rect or rect_float, assume this is already checked */
-
-	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 (outF) {
-		/* sample including outside of edges of image */
-		if (x1 < 0 || y1 < 0) row1 = empty;
-		else row1 = in->rect_float + in->x * y1 * 4 + 4 * x1;
-		
-		if (x1 < 0 || y2 > in->y - 1) row2 = empty;
-		else row2 = in->rect_float + in->x * y2 * 4 + 4 * x1;
-		
-		if (x2 > in->x - 1 || y1 < 0) row3 = empty;
-		else row3 = in->rect_float + in->x * y1 * 4 + 4 * x2;
-		
-		if (x2 > in->x - 1 || y2 > in->y - 1) row4 = empty;
-		else row4 = in->rect_float + in->x * y2 * 4 + 4 * x2;
-
-		a = u - floorf(u);
-		b = v - floorf(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];
+		BLI_bilinear_interpolation_fl(in->rect_float, outF, in->x, in->y, 4, u, v);
 	}
-	if (outI) {
-		/* 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 - floorf(u);
-		b = v - floorf(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);
-		
-		/* need to add 0.5 to avoid rounding down (causes darken with the smear brush)
-		 * tested with white images and this should not wrap back to zero */
-		outI[0] = (ma_mb * row1I[0] + a_mb * row3I[0] + ma_b * row2I[0] + a_b * row4I[0]) + 0.5f;
-		outI[1] = (ma_mb * row1I[1] + a_mb * row3I[1] + ma_b * row2I[1] + a_b * row4I[1]) + 0.5f;
-		outI[2] = (ma_mb * row1I[2] + a_mb * row3I[2] + ma_b * row2I[2] + a_b * row4I[2]) + 0.5f;
-		outI[3] = (ma_mb * row1I[3] + a_mb * row3I[3] + ma_b * row2I[3] + a_b * row4I[3]) + 0.5f;
+	else {
+		BLI_bilinear_interpolation_char((unsigned char*) in->rect, outI, in->x, in->y, 4, u, v);
 	}
 }