Introduce _substitute_pixel to simplify everything

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Unreleased
 
+## Optimisations
+
+-   Added `_substitute_pixel` to perform substitution for a single pixel, and replaced the current implementation of `substitution` algorithm with the same ([#78](https://github.com/Saransh-cpp/ChaoticEncryption.jl/pull/78), @Saransh-cpp)
+
 # ChaoticEncryption v0.3.1
 
 ## Optimisations

docs/make.jl

@@ -22,7 +22,6 @@ makedocs(
         ],
         "Developer Documentation" => [
             "Encryption/decryption algorithms" => "devdocs/algorithms.md",
-            "Utility functions" => "devdocs/utils.md"
         ]
     ]
 )

docs/src/devdocs/algorithms.md

@@ -2,11 +2,22 @@
 
 Developer documentation for encryption and decryption algorithms.
 
+These lower level APIs can also be used by the users, but are not recommended
+for beginners.
+
 ```@docs
 ChaoticEncryption._substitution(
     image::Union{String,Array{RGB{N0f8},2}},
     keys::Vector{Int64},
     type::Symbol;
-    path_for_result::String="./encrypted.png"
+    path_for_result::String="./encrypted.png",
+    inplace=false,
+)
+```
+
+```@docs
+ChaoticEncryption._substitute_pixel(
+    pixel::RGB,
+    key::Int64
 )
 ```

src/substitution.jl

@@ -1,7 +1,5 @@
 using Images
 
-include("./utils.jl")
-
 
 """
     _substitution(image, keys, type; path_for_result="./encrypted.png")
@@ -46,21 +44,11 @@ function _substitution(
         @info "DECRYPTING"
     end
 
-    # generate arrays for r, g, b values of each pixel
-    r = Array{Int64}(undef, height, width)
-    g = Array{Int64}(undef, height, width)
-    b = Array{Int64}(undef, height, width)
-
-    # resize keys for broadcasting
+    # reshape keys for broadcasting
     keys = reshape(keys, height, width)
 
-    # collect all r, g, b values without loop
-    @. r = trunc(Int, _redify(image) * 255)
-    @. g = trunc(Int, _greenify(image) * 255)
-    @. b = trunc(Int, _blueify(image) * 255)
-
-    # XOR all r, g, b values and replace the values in image
-    @. image = _imageify((r ⊻ keys) / 255, (g ⊻ keys) / 255, (b ⊻ keys) / 255)
+    # substitute all pixels in one go
+    @. image = _substitute_pixel(image, keys)
 
     if type == :encrypt
         @info "ENCRYPTED"
@@ -73,6 +61,29 @@ function _substitution(
 end
 
 
+"""
+    _substitute_pixel(pixel::RGB, key::Int64)
+
+Returns the pixel after XORing the R, G, and B values with the key.
+Specifically developed to return an `Array` (or the complete image)
+of XORed RGB values in one go.
+
+See [`_substitution`](@ref) for more details.
+
+# Arguments
+- `pixel::RGB`: Pixel value with r, g, and b components.
+- `key::Int64`: The key.
+
+# Returns
+- `pixel::RGB`: Substituted pixel.
+"""
+_substitute_pixel(pixel::RGB, key::Int64) = RGB(
+    (trunc(Int, pixel.r * 255) ⊻ key) / 255,
+    (trunc(Int, pixel.g * 255) ⊻ key) / 255,
+    (trunc(Int, pixel.b * 255) ⊻ key) / 255
+)
+
+
 """
     substitution_encryption(image, keys; path_for_result="./encrypted.png")