incorporate review comments

examples/fast_blur/.gitignore

@@ -1 +1,2 @@
-lenna_blurred.png
+mandril_color_blurred.tif
+

examples/fast_blur/main.rs

@@ -1,12 +1,13 @@
 use image::ImageReader;
 
 fn main() {
- let img = ImageReader::open("examples/fast_blur/lenna.png")
+ let img = ImageReader::open("examples/fast_blur/mandril_color.tif")
  .unwrap()
  .decode()
  .unwrap();
 
  let img2 = img.fast_blur(10.0);
 
- img2.save("examples/fast_blur/lenna_blurred.png").unwrap();
+ img2.save("examples/fast_blur/mandril_color_blurred.tif")
+ .unwrap();
 }

src/imageops/fast_blur.rs

@@ -10,20 +10,24 @@ pub fn fast_blur<P: Pixel>(
  sigma: f32,
 ) -> ImageBuffer<P, Vec<P::Subpixel>> {
  let (width, height) = image_buffer.dimensions();
+
+ if width == 0 || height == 0 {
+ return image_buffer.clone();
+ }
  let mut samples = image_buffer.as_flat_samples().samples.to_vec();
  let num_passes = 3;
 
  let boxes = boxes_for_gauss(sigma, num_passes);
 
  for radius in boxes.iter().take(num_passes) {
- let horizontally_blurred_transposed = my_fast_horizontal_blur::<P::Subpixel>(
+ let horizontally_blurred_transposed = horizontal_fast_blur_half::<P::Subpixel>(
  &samples,
  width as usize,
  height as usize,
  *radius,
  P::CHANNEL_COUNT as usize,
  );
- samples = my_fast_horizontal_blur::<P::Subpixel>(
+ samples = horizontal_fast_blur_half::<P::Subpixel>(
  &horizontally_blurred_transposed,
  height as usize,
  width as usize,
@@ -60,7 +64,7 @@ fn channel_idx(channel: usize, idx: usize, channel_num: usize) -> usize {
  channel_num * idx + channel
 }
 
-fn my_fast_horizontal_blur<P: Primitive>(
+fn horizontal_fast_blur_half<P: Primitive>(
  samples: &[P],
  width: usize,
  height: usize,
@@ -75,18 +79,26 @@ fn my_fast_horizontal_blur<P: Primitive>(
  let min_value = P::DEFAULT_MIN_VALUE.to_f32().unwrap();
  let max_value = P::DEFAULT_MAX_VALUE.to_f32().unwrap();
 
- for i in 0..height {
+ for row in 0..height {
  for (channel, value) in vals.iter_mut().enumerate().take(channel_num) {
  *value = ((-(r as isize))..(r + 1) as isize)
  .map(|x| {
- extended_f(samples, width, height, x, i as isize, channel, channel_num)
- .to_f32()
- .unwrap_or(0.0)
+ extended_f(
+ samples,
+ width,
+ height,
+ x,
+ row as isize,
+ channel,
+ channel_num,
+ )
+ .to_f32()
+ .unwrap_or(0.0)
  })
  .sum()
  }
 
- for j in 0..width {
+ for column in 0..width {
  for channel in 0..channel_num {
  let val = vals[channel] / (2.0 * r as f32 + 1.0);
  let val = if val < min_value {
@@ -98,14 +110,20 @@ fn my_fast_horizontal_blur<P: Primitive>(
  };
  let val = P::from(val).unwrap();
 
- out_samples[channel_idx(channel, i + j * height, channel_num)] = val;
+ let destination_row = column;
+ let destination_column = row;
+ out_samples[channel_idx(
+ channel,
+ destination_column + destination_row * height,
+ channel_num,
+ )] = val;
  vals[channel] = vals[channel]
  - extended_f(
  samples,
  width,
  height,
- j as isize - r as isize,
- i as isize,
+ column as isize - r as isize,
+ row as isize,
  channel,
  channel_num,
  )
@@ -115,8 +133,8 @@ fn my_fast_horizontal_blur<P: Primitive>(
  samples,
  width,
  height,
- { j + r + 1 } as isize,
- i as isize,
+ { column + r + 1 } as isize,
+ row as isize,
  channel,
  channel_num,
  )

src/imageops/mod.rs

@@ -481,23 +481,41 @@ mod tests {
  }
 
  #[test]
- /// Test blur doesn't panick when passed 0.0
+ /// Test blur doesn't panic when passed 0.0
  fn test_blur_zero() {
  let image = RgbaImage::new(50, 50);
  let _ = super::blur(&image, 0.0);
  }
 
  #[test]
- /// Test blur doesn't panick when passed 0.0
+ /// Test fast blur doesn't panic when passed 0.0
  fn test_fast_blur_zero() {
  let image = RgbaImage::new(50, 50);
- let _ = super::fast_blur(&image, -1.0);
+ let _ = super::fast_blur(&image, 0.0);
  }
 
  #[test]
- /// Test blur doesn't panick when passed negative numbers
+ /// Test fast blur doesn't panic when passed negative numbers
  fn test_fast_blur_negative() {
  let image = RgbaImage::new(50, 50);
  let _ = super::fast_blur(&image, -1.0);
  }
+
+ #[test]
+ /// Test fast blur doesn't panic when sigma produces boxes larger than the image
+ fn test_fast_large_sigma() {
+ let image = RgbaImage::new(1, 1);
+ let _ = super::fast_blur(&image, 50.0);
+ }
+
+ #[test]
+ /// Test blur doesn't panic when passed an empty image (any direction)
+ fn test_fast_blur_empty() {
+ let image = RgbaImage::new(0, 0);
+ let _ = super::fast_blur(&image, 1.0);
+ let image = RgbaImage::new(20, 0);
+ let _ = super::fast_blur(&image, 1.0);
+ let image = RgbaImage::new(0, 20);
+ let _ = super::fast_blur(&image, 1.0);
+ }
 }