Fix Image nearest and cubic resizing bias

Author: beicause

core/io/image.cpp

@@ -801,24 +801,21 @@ static void _scale_cubic(const uint8_t *__restrict p_src, uint8_t *__restrict p_
 
 	for (uint32_t y = 0; y < p_dst_height; y++) {
 		// Y coordinates
-		oy = (double)y * yfac - 0.5f;
+		oy = (double)(y + 0.5) * yfac - 0.5;
 		oy1 = (int)oy;
 		dy = oy - (double)oy1;
 
 		for (uint32_t x = 0; x < p_dst_width; x++) {
 			// X coordinates
-			ox = (double)x * xfac - 0.5f;
+			ox = (double)(x + 0.5) * xfac - 0.5;
 			ox1 = (int)ox;
 			dx = ox - (double)ox1;
 
 			// initial pixel value
 
 			T *__restrict dst = ((T *)p_dst) + (y * p_dst_width + x) * CC;
 
-			double color[CC];
-			for (int i = 0; i < CC; i++) {
-				color[i] = 0;
-			}
+			double color[CC] = {};
 
 			for (int n = -1; n < 3; n++) {
 				// get Y coefficient
@@ -961,11 +958,11 @@ static void _scale_bilinear(const uint8_t *__restrict p_src, uint8_t *__restrict
 template <int CC, typename T>
 static void _scale_nearest(const uint8_t *__restrict p_src, uint8_t *__restrict p_dst, uint32_t p_src_width, uint32_t p_src_height, uint32_t p_dst_width, uint32_t p_dst_height) {
 	for (uint32_t i = 0; i < p_dst_height; i++) {
-		uint32_t src_yofs = i * p_src_height / p_dst_height;
+		uint32_t src_yofs = (i + 0.5) * p_src_height / p_dst_height;
 		uint32_t y_ofs = src_yofs * p_src_width * CC;
 
 		for (uint32_t j = 0; j < p_dst_width; j++) {
-			uint32_t src_xofs = j * p_src_width / p_dst_width;
+			uint32_t src_xofs = (j + 0.5) * p_src_width / p_dst_width;
 			src_xofs *= CC;
 
 			for (uint32_t l = 0; l < CC; l++) {