Merge pull request #559 from stefan-k/master

several color conversion functions, imedge, imstretch, imlaplacian, laplacian of gaussian

examples/image.jl

@@ -131,7 +131,7 @@ end
 
 imshow(img) = imshow(img, [])
 
-function imadjustintensity(img, range)
+function imadjustintensity{T}(img::Array{T,2}, range)
     if length(range) == 0
         range = [min(img) max(img)]
     elseif length(range) == 1
@@ -199,8 +199,16 @@ end
 
 imlaplacian() = imlaplacian("nodiagonals")
 
+# more general version
+function imlaplacian(alpha::Number)
+    lc = alpha/(1 + alpha)
+    lb = (1 - alpha)/(1 + alpha)
+    lm = -4/(1 + alpha)
+    return [lc lb lc; lb lm lb; lc lb lc]
+end
+
 # 2D gaussian filter kernel
-function gaussian2d(sigma, filter_size)
+function gaussian2d(sigma::Number, filter_size)
     if length(filter_size) == 0
         # choose 'good' size 
         m = 4*ceil(sigma)+1
@@ -217,17 +225,25 @@ function gaussian2d(sigma, filter_size)
     return g/sum(g)
 end
 
-gaussian2d(sigma) = gaussian2d(sigma, [])
+gaussian2d(sigma::Number) = gaussian2d(sigma, [])
 gaussian2d() = gaussian2d(0.5, [])
 
 # difference of gaussian
-function imdog(sigma)
+function imdog(sigma::Number)
     m = 4*ceil(sqrt(2)*sigma)+1
     return gaussian2d(sqrt(2)*sigma, [m m]) - gaussian2d(sigma, [m m])
 end
 
 imdog() = imdog(0.5)
 
+# laplacian of gaussian
+function imlog(sigma::Number)
+    m = 4*ceil(sigma)+1
+    return [((x^2+y^2-sigma^2)/sigma^4)*exp(-(x^2+y^2)/(2*sigma^2)) | x=-floor(m/2):floor(m/2), y=-floor(m/2):floor(m/2)]
+end
+
+imlog() = imlog(0.5)
+
 # Sum of squared differences
 function ssd{T}(A::Array{T}, B::Array{T})
     return sum((A-B).^2)
@@ -376,3 +392,106 @@ imgaussiannoise{T}(img::Array{T}) = imgaussiannoise(img, 0.01, 0)
 # 'illustrates' fourier transform
 ftshow{T}(A::Array{T,2}) = imshow(log(1+abs(fftshift(A))),[])
 
+function rgb2ntsc{T}(img::Array{T})
+    trans = [0.299 0.587 0.114; 0.596 -0.274 -0.322; 0.211 -0.523 0.312]
+    out = zeros(T, size(img))
+    for i = 1:size(img,1), j = 1:size(img,2)
+        out[i,j,:] = trans * squeeze(img[i,j,:])
+    end
+    return out
+end
+
+function ntsc2rgb{T}(img::Array{T})
+    trans = [1 0.956 0.621; 1 -0.272 -0.647; 1 -1.106 1.703]
+    out = zeros(T, size(img))
+    for i = 1:size(img,1), j = 1:size(img,2)
+        out[i,j,:] = trans * squeeze(img[i,j,:])
+    end
+    return out
+end
+
+function rgb2ycbcr{T}(img::Array{T})
+    trans = [65.481 128.533 24.966; -37.797 -74.203 112; 112 -93.786 -18.214]
+    offset = [16.0; 128.0; 128.0]
+    out = zeros(T, size(img))
+    for i = 1:size(img,1), j = 1:size(img,2)
+        out[i,j,:] = offset + trans * squeeze(img[i,j,:])
+    end
+    return out
+end
+
+function ycbcr2rgb{T}(img::Array{T})
+    trans = inv([65.481 128.533 24.966; -37.797 -74.203 112; 112 -93.786 -18.214])
+    offset = [16.0; 128.0; 128.0]
+    out = zeros(T, size(img))
+    for i = 1:size(img,1), j = 1:size(img,2)
+        out[i,j,:] = trans * (squeeze(img[i,j,:]) - offset)
+    end
+    return out
+end
+
+function imcomplement{T}(img::Array{T})
+    return 1 - img
+end
+
+function rgb2hsi{T}(img::Array{T})
+    R = img[:,:,1]
+    G = img[:,:,2]
+    B = img[:,:,3]
+    H = acos((1/2*(2*R - G - B)) ./ (((R - G).^2 + (R - B).*(G - B)).^(1/2)+eps(T))) 
+    H[B > G] = 2*pi - H[B > G]
+    H /= 2*pi
+    rgb_sum = R + G + B
+    rgb_sum[rgb_sum == 0] = eps(T)
+    S = 1 - 3./(rgb_sum).*min(R, G, B)
+    H[S == 0] = 0
+    I = 1/3*(R + G + B)
+    return cat(3, H, S, I)
+end
+
+function hsi2rgb{T}(img::Array{T})
+    H = img[:,:,1]*2*pi
+    S = img[:,:,2]
+    I = img[:,:,3]
+    R = zeros(T, size(img,1), size(img,2))
+    G = zeros(T, size(img,1), size(img,2))
+    B = zeros(T, size(img,1), size(img,2))
+    RG = 0 <= H < 2*pi/3
+    GB = 2*pi/3 <= H < 4*pi/3
+    BR = 4*pi/3 <= H < 2*pi
+    # RG sector
+    B[RG] = I[RG].*(1 - S[RG])
+    R[RG] = I[RG].*(1 + (S[RG].*cos(H[RG]))./cos(pi/3 - H[RG]))
+    G[RG] = 3*I[RG] - R[RG] - B[RG]
+    # GB sector
+    R[GB] = I[GB].*(1 - S[GB])
+    G[GB] = I[GB].*(1 + (S[GB].*cos(H[GB] - pi/3))./cos(H[GB]))
+    B[GB] = 3*I[GB] - R[GB] - G[GB]
+    # BR sector
+    G[BR] = I[BR].*(1 - S[BR])
+    B[BR] = I[BR].*(1 + (S[BR].*cos(H[BR] - 2*pi/3))./cos(-pi/3 - H[BR]))
+    R[BR] = 3*I[BR] - G[BR] - B[BR]
+    return cat(3, R, G, B)
+end
+
+function imstretch{T}(img::Array{T,2}, m::Number, slope::Number)
+    return 1./(1 + (m./(img + eps(T))).^slope)
+end
+
+function imedge{T}(img::Array{T}, method::String, border::String)
+    # needs more methods
+    if method == "sobel"
+        s1, s2 = sobel()
+        img1 = imfilter(img, s1, border)
+        img2 = imfilter(img, s2, border)
+        return img1, img2, sqrt(img1.^2 + img2.^2), atan2(img2, img1)
+    elseif method == "prewitt"
+        s1, s2 = prewitt()
+        img1 = imfilter(img, s1, border)
+        img2 = imfilter(img, s2, border)
+        return img1, img2, sqrt(img1.^2 + img2.^2), atan2(img2, img1)
+    end
+end
+
+imedge{T}(img::Array{T}, method::String) = imedge(img, method, "replicate")
+imedge{T}(img::Array{T}) = imedge(img, "sobel", "replicate")