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Add experimental sharpness calc to stats #2251

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Lovell Fuller
2020-06-12 11:25:57 +01:00
parent 9431029917
commit 8f5495a446
6 changed files with 49 additions and 2 deletions
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12
src/stats.cc
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@@ -75,8 +75,17 @@ class StatsWorker : public Napi::AsyncWorker {
baton->isOpaque = false;
}
}
// Convert to greyscale
vips::VImage greyscale = image.colourspace(VIPS_INTERPRETATION_B_W)[0];
// Estimate entropy via histogram of greyscale value frequency
baton->entropy = std::abs(image.colourspace(VIPS_INTERPRETATION_B_W)[0].hist_find().hist_entropy());
baton->entropy = std::abs(greyscale.hist_find().hist_entropy());
// Estimate sharpness via standard deviation of greyscale laplacian
VImage laplacian = VImage::new_matrixv(3, 3,
0.0, 1.0, 0.0,
1.0, -4.0, 1.0,
0.0, 1.0, 0.0);
laplacian.set("scale", 9.0);
baton->sharpness = greyscale.conv(laplacian).deviate();
} catch (vips::VError const &err) {
(baton->err).append(err.what());
}
@@ -123,6 +132,7 @@ class StatsWorker : public Napi::AsyncWorker {
info.Set("channels", channels);
info.Set("isOpaque", baton->isOpaque);
info.Set("entropy", baton->entropy);
info.Set("sharpness", baton->sharpness);
Callback().MakeCallback(Receiver().Value(), { env.Null(), info });
} else {
Callback().MakeCallback(Receiver().Value(), { Napi::Error::New(env, baton->err).Value() });

4
src/stats.h
View File

@@ -47,13 +47,15 @@ struct StatsBaton {
std::vector<ChannelStats> channelStats;
bool isOpaque;
double entropy;
double sharpness;
std::string err;
StatsBaton():
input(nullptr),
isOpaque(true),
entropy(0.0)
entropy(0.0),
sharpness(0.0)
{}
};