diff --git a/src/cr-image/grayscale_image.cr b/src/cr-image/grayscale_image.cr
index def0488..f3fe36a 100644
--- a/src/cr-image/grayscale_image.cr
+++ b/src/cr-image/grayscale_image.cr
@@ -71,6 +71,13 @@ class CrImage::GrayscaleImage < CrImage::Image
     nil
   end
 
+  # Run provided block with the `ChannelType::Gray` channels and channel types.
+  def each_channel(& : (Array(UInt8), ChannelType) -> Nil) : Nil
+    yield @gray, ChannelType::Gray
+    yield @alpha, ChannelType::Alpha
+    nil
+  end
+
   record Pixel,
     gray : UInt8,
     alpha : UInt8
diff --git a/src/cr-image/image.cr b/src/cr-image/image.cr
index 7d088d5..f806259 100644
--- a/src/cr-image/image.cr
+++ b/src/cr-image/image.cr
@@ -48,6 +48,9 @@ abstract class CrImage::Image
   # Run provided block on each channel supported by this image.
   abstract def each_color_channel(& : (Array(UInt8), ChannelType) -> Nil) : Nil
 
+  # Run provided block on each channel supported by this image.
+  abstract def each_channel(& : (Array(UInt8), ChannelType) -> Nil) : Nil
+
   # Get the `Array(UInt8)` corresponding to `channel_type`)
   abstract def [](channel_type : ChannelType) : Array(UInt8)
   # Set the `Array(UInt8)` corresponding to `channel_type`) to `channel`
diff --git a/src/cr-image/operation/bilinear_resize.cr b/src/cr-image/operation/bilinear_resize.cr
index f711510..cd6f646 100644
--- a/src/cr-image/operation/bilinear_resize.cr
+++ b/src/cr-image/operation/bilinear_resize.cr
@@ -22,8 +22,7 @@ module CrImage::Operation::BilinearResize
     x_ratio = width > 1 ? (@width - 1) / (width - 1) : 0
     y_ratio = height > 1 ? (@height - 1) / (height - 1) : 0
 
-    # TODO: resize alpha channel
-    each_color_channel do |channel, channel_type|
+    each_channel do |channel, channel_type|
       resized_channel = Array.new(width * height) { 0u8 }
 
       height.times do |h|
diff --git a/src/cr-image/operation/crop.cr b/src/cr-image/operation/crop.cr
index 0cfdda6..79f6535 100644
--- a/src/cr-image/operation/crop.cr
+++ b/src/cr-image/operation/crop.cr
@@ -30,7 +30,7 @@ module CrImage::Operation::Crop
   end
 
   def crop!(x : Int32, y : Int32, new_width : Int32, new_height : Int32) : self
-    each_color_channel do |channel, channel_type|
+    each_channel do |channel, channel_type|
       self[channel_type] = UInt8Map.new(width, channel)[x, new_width, y, new_height].raw
     end
 
diff --git a/src/cr-image/operation/pad.cr b/src/cr-image/operation/pad.cr
index 0a7a1e1..b008975 100644
--- a/src/cr-image/operation/pad.cr
+++ b/src/cr-image/operation/pad.cr
@@ -16,24 +16,14 @@ module CrImage::Operation::Pad
   end
 
   def pad!(all : Int32 = 0, *, top : Int32 = 0, bottom : Int32 = 0, left : Int32 = 0, right : Int32 = 0, pad_type : EdgePolicy = EdgePolicy::Black) : self
-    # mem_start = GC.stats.total_bytes
-    new_width = width
-    new_height = height
-    # puts "Memory start: #{GC.stats.total_bytes - mem_start}"
-    # TODO: resize alpha channel
-    each_color_channel do |channel, channel_type|
-      padded = UInt8Map.new(width, channel).pad(all, top: top, bottom: bottom, left: left, right: right, pad_type: pad_type)
+    orig_width = width
+    each_channel do |channel, channel_type|
+      padded = UInt8Map.new(orig_width, channel).pad(all, top: top, bottom: bottom, left: left, right: right, pad_type: pad_type)
       self[channel_type] = padded.raw
-      new_width = padded.width
-      new_height = padded.height
-      # puts "Memory after #{channel_type}: #{GC.stats.total_bytes - mem_start}"
+      @width = padded.width
+      @height = padded.height
     end
 
-    # puts "Memory final: #{GC.stats.total_bytes - mem_start}"
-
-    @width = new_width
-    @height = new_height
-
     self
   end
 end
diff --git a/src/cr-image/rgba_image.cr b/src/cr-image/rgba_image.cr
index 1cbd3d0..4639ce9 100644
--- a/src/cr-image/rgba_image.cr
+++ b/src/cr-image/rgba_image.cr
@@ -30,6 +30,15 @@ class CrImage::RGBAImage < CrImage::Image
     nil
   end
 
+  # Run provided block with the `ChannelType::Red`, `ChannelType::Green`, and `ChannelType::Blue` channels.
+  def each_channel(& : (Array(UInt8), ChannelType) -> Nil) : Nil
+    yield @red, ChannelType::Red
+    yield @green, ChannelType::Green
+    yield @blue, ChannelType::Blue
+    yield @alpha, ChannelType::Alpha
+    nil
+  end
+
   record Pixel,
     red : UInt8,
     green : UInt8,