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Fix Brightness, Hue, and Saturation effects (#889)

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* Fix Brightness, Hue, and Saturation effects to fully support pre-multiplied colors (when alpha channel found)

* Fixing whitespace on effects
This commit is contained in:
Jonathan Thomas
2022-12-21 22:18:42 -06:00
committed by GitHub
parent 4fbb4392ba
commit 99aab0a12b
3 changed files with 50 additions and 24 deletions
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27
src/effects/Brightness.cpp
View File

@@ -63,16 +63,29 @@ std::shared_ptr<openshot::Frame> Brightness::GetFrame(std::shared_ptr<openshot::
// Compute contrast adjustment factor
float factor = (259 * (contrast_value + 255)) / (255 * (259 - contrast_value));
// Get RGB pixels from image and apply constrained contrast adjustment
int R = constrain((factor * (pixels[pixel * 4] - 128)) + 128);
int G = constrain((factor * (pixels[pixel * 4 + 1] - 128)) + 128);
int B = constrain((factor * (pixels[pixel * 4 + 2] - 128)) + 128);
// (Don't modify Alpha value)
// Calculate alpha % (to be used for removing pre-multiplied alpha value)
int A = pixels[pixel * 4 + 3];
float alpha_percent = A / 255.0;
// Get RGB values, and remove pre-multiplied alpha
unsigned char R = pixels[pixel * 4 + 0] / alpha_percent;
unsigned char G = pixels[pixel * 4 + 1] / alpha_percent;
unsigned char B = pixels[pixel * 4 + 2] / alpha_percent;
// Apply constrained contrast adjustment
R = constrain((factor * (R - 128)) + 128);
G = constrain((factor * (G - 128)) + 128);
B = constrain((factor * (B - 128)) + 128);
// Adjust brightness and write constrained values back to image
pixels[pixel * 4] = constrain(R + (255 * brightness_value));
pixels[pixel * 4 + 0] = constrain(R + (255 * brightness_value));
pixels[pixel * 4 + 1] = constrain(G + (255 * brightness_value));
pixels[pixel * 4 + 2] = constrain(B + (255 * brightness_value));
// Pre-multiply the alpha back into the color channels
pixels[pixel * 4 + 0] *= alpha_percent;
pixels[pixel * 4 + 1] *= alpha_percent;
pixels[pixel * 4 + 2] *= alpha_percent;
}
// return the modified frame
@@ -143,7 +156,7 @@ std::string Brightness::PropertiesJSON(int64_t requested_frame) const {
// Keyframes
root["brightness"] = add_property_json("Brightness", brightness.GetValue(requested_frame), "float", "", &brightness, -1.0, 1.0, false, requested_frame);
root["contrast"] = add_property_json("Contrast", contrast.GetValue(requested_frame), "float", "", &contrast, 0.0, 100.0, false, requested_frame);
root["contrast"] = add_property_json("Contrast", contrast.GetValue(requested_frame), "float", "", &contrast, -128, 128.0, false, requested_frame);
// Set the parent effect which properties this effect will inherit
root["parent_effect_id"] = add_property_json("Parent", 0.0, "string", info.parent_effect_id, NULL, -1, -1, false, requested_frame);

17
src/effects/Hue.cpp
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@@ -69,15 +69,24 @@ std::shared_ptr<openshot::Frame> Hue::GetFrame(std::shared_ptr<openshot::Frame>
#pragma omp parallel for shared (pixels)
for (int pixel = 0; pixel < pixel_count; ++pixel)
{
// Get the RGB values from the pixel (ignore the alpha channel)
int R = pixels[pixel * 4];
int G = pixels[pixel * 4 + 1];
int B = pixels[pixel * 4 + 2];
// Calculate alpha % (to be used for removing pre-multiplied alpha value)
int A = pixels[pixel * 4 + 3];
float alpha_percent = A / 255.0;
// Get RGB values, and remove pre-multiplied alpha
int R = pixels[pixel * 4 + 0] / alpha_percent;
int G = pixels[pixel * 4 + 1] / alpha_percent;
int B = pixels[pixel * 4 + 2] / alpha_percent;
// Multiply each color by the hue rotation matrix
pixels[pixel * 4] = constrain(R * matrix[0] + G * matrix[1] + B * matrix[2]);
pixels[pixel * 4 + 1] = constrain(R * matrix[2] + G * matrix[0] + B * matrix[1]);
pixels[pixel * 4 + 2] = constrain(R * matrix[1] + G * matrix[2] + B * matrix[0]);
// Pre-multiply the alpha back into the color channels
pixels[pixel * 4 + 0] *= alpha_percent;
pixels[pixel * 4 + 1] *= alpha_percent;
pixels[pixel * 4 + 2] *= alpha_percent;
}
// return the modified frame

30
src/effects/Saturation.cpp
View File

@@ -72,10 +72,14 @@ std::shared_ptr<openshot::Frame> Saturation::GetFrame(std::shared_ptr<openshot::
#pragma omp parallel for shared (pixels)
for (int pixel = 0; pixel < pixel_count; ++pixel)
{
// Get the RGB values from the pixel
int R = pixels[pixel * 4];
int G = pixels[pixel * 4 + 1];
int B = pixels[pixel * 4 + 2];
// Calculate alpha % (to be used for removing pre-multiplied alpha value)
int A = pixels[pixel * 4 + 3];
float alpha_percent = A / 255.0;
// Get RGB values, and remove pre-multiplied alpha
int R = pixels[pixel * 4 + 0] / alpha_percent;
int G = pixels[pixel * 4 + 1] / alpha_percent;
int B = pixels[pixel * 4 + 2] / alpha_percent;
/*
* Common saturation adjustment
@@ -87,14 +91,9 @@ std::shared_ptr<openshot::Frame> Saturation::GetFrame(std::shared_ptr<openshot::
(B * B * pB) );
// Adjust the saturation
R = p + (R - p) * saturation_value;
G = p + (G - p) * saturation_value;
B = p + (B - p) * saturation_value;
// Constrain the value from 0 to 255
R = constrain(R);
G = constrain(G);
B = constrain(B);
R = constrain(p + (R - p) * saturation_value);
G = constrain(p + (G - p) * saturation_value);
B = constrain(p + (B - p) * saturation_value);
/*
* Color-separated saturation adjustment
@@ -134,9 +133,14 @@ std::shared_ptr<openshot::Frame> Saturation::GetFrame(std::shared_ptr<openshot::
B = constrain(B);
// Set all pixels to new value
pixels[pixel * 4] = R;
pixels[pixel * 4 + 0] = R;
pixels[pixel * 4 + 1] = G;
pixels[pixel * 4 + 2] = B;
// Pre-multiply the alpha back into the color channels
pixels[pixel * 4 + 0] *= alpha_percent;
pixels[pixel * 4 + 1] *= alpha_percent;
pixels[pixel * 4 + 2] *= alpha_percent;
}
// return the modified frame