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Ensure correct Gaussian blur before affine #121

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Use double sigma instead of int radius for blur
This commit is contained in:
Lovell Fuller
2014-11-20 13:59:39 +00:00
parent 177a4f574c
commit b7c7fc22f3
6 changed files with 57 additions and 38 deletions
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51
src/resize.cc
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@@ -51,7 +51,7 @@ struct ResizeBaton {
std::string interpolator;
double background[4];
bool flatten;
int blurRadius;
double blurSigma;
int sharpenRadius;
double sharpenFlat;
double sharpenJagged;
@@ -78,7 +78,7 @@ struct ResizeBaton {
canvas(Canvas::CROP),
gravity(0),
flatten(false),
blurRadius(0),
blurSigma(0.0),
sharpenRadius(0),
sharpenFlat(1.0),
sharpenJagged(2.0),
@@ -364,22 +364,33 @@ class ResizeWorker : public NanAsyncWorker {
}
// Use vips_affine with the remaining float part
if (residual != 0) {
// Apply variable blur radius of floor(residual) before large affine reductions
if (residual >= 1) {
VipsImage *blurred;
if (vips_gaussblur(image, &blurred, floor(residual), NULL)) {
return Error(baton, hook);
if (residual != 0.0) {
// Apply Gaussian blur before large affine reductions
if (residual < 1.0) {
// Calculate standard deviation
double sigma = ((1.0 / residual) - 0.5) / 1.5;
if (sigma >= 0.3) {
// Create Gaussian function for standard deviation
VipsImage *gaussian;
if (vips_gaussmat(&gaussian, sigma, 0.2, "separable", TRUE, "integer", TRUE, NULL)) {
return Error(baton, hook);
}
vips_object_local(hook, gaussian);
// Apply Gaussian function
VipsImage *blurred;
if (vips_convsep(image, &blurred, gaussian, "precision", VIPS_PRECISION_INTEGER, NULL)) {
return Error(baton, hook);
}
vips_object_local(hook, blurred);
image = blurred;
}
vips_object_local(hook, blurred);
image = blurred;
}
// Create interpolator - "bilinear" (default), "bicubic" or "nohalo"
VipsInterpolate *interpolator = vips_interpolate_new(baton->interpolator.c_str());
vips_object_local(hook, interpolator);
// Perform affine transformation
VipsImage *affined;
if (vips_affine(image, &affined, residual, 0, 0, residual, "interpolate", interpolator, NULL)) {
if (vips_affine(image, &affined, residual, 0.0, 0.0, residual, "interpolate", interpolator, NULL)) {
return Error(baton, hook);
}
vips_object_local(hook, affined);
@@ -502,10 +513,10 @@ class ResizeWorker : public NanAsyncWorker {
}
// Blur
if (baton->blurRadius != 0) {
if (baton->blurSigma != 0.0) {
VipsImage *blurred;
if (baton->blurRadius == -1) {
// Fast, mild blur
if (baton->blurSigma < 0.0) {
// Fast, mild blur - averages neighbouring pixels
VipsImage *blur = vips_image_new_matrixv(3, 3,
1.0, 1.0, 1.0,
1.0, 1.0, 1.0,
@@ -517,7 +528,15 @@ class ResizeWorker : public NanAsyncWorker {
}
} else {
// Slower, accurate Gaussian blur
if (vips_gaussblur(image, &blurred, baton->blurRadius, NULL)) {
// Create Gaussian function for standard deviation
VipsImage *gaussian;
if (vips_gaussmat(&gaussian, baton->blurSigma, 0.2, "separable", TRUE, "integer", TRUE, NULL)) {
return Error(baton, hook);
}
vips_object_local(hook, gaussian);
// Apply Gaussian function
VipsImage *blurred;
if (vips_convsep(image, &blurred, gaussian, "precision", VIPS_PRECISION_INTEGER, NULL)) {
return Error(baton, hook);
}
}
@@ -847,7 +866,7 @@ NAN_METHOD(resize) {
baton->interpolator = *String::Utf8Value(options->Get(NanNew<String>("interpolator"))->ToString());
// Operators
baton->flatten = options->Get(NanNew<String>("flatten"))->BooleanValue();
baton->blurRadius = options->Get(NanNew<String>("blurRadius"))->Int32Value();
baton->blurSigma = options->Get(NanNew<String>("blurSigma"))->NumberValue();
baton->sharpenRadius = options->Get(NanNew<String>("sharpenRadius"))->Int32Value();
baton->sharpenFlat = options->Get(NanNew<String>("sharpenFlat"))->NumberValue();
baton->sharpenJagged = options->Get(NanNew<String>("sharpenJagged"))->NumberValue();