From e10d4a731712b22cae56353ae5215b63d11c8e96 Mon Sep 17 00:00:00 2001
From: Elian Dib <elian.dib@inria.fr>
Date: Sat, 3 Aug 2019 11:38:58 +0200
Subject: [PATCH] Simplified rgb<--->ycbcr conversions
---
rgb2ycbcr.m | 47 ++++++++++++++++++++++++++++++++++++++++++++++-
ycbcr2rgb.m | 47 ++++++++++++++++++++++++++++++++++++++++++++++-
2 files changed, 92 insertions(+), 2 deletions(-)
diff --git a/rgb2ycbcr.m b/rgb2ycbcr.m
index 1c5a925..71c1bfe 100644
--- a/rgb2ycbcr.m
+++ b/rgb2ycbcr.m
@@ -1 +1,46 @@
-% Author : Hadi Amirpour
% email : hadi.amirpour@gmail.com
% Copyright(c) EmergIMG,
% Universidade da Beira Interior
% script for RGB 444 to YCbCr 444 color space conversion in n bits
% Input:
% 1-rgb ---> RGB image in double format
% 2-n ---> number of the bits, this number should be either 8 or 10
% Output:
% 1-ycbcr ---> YCbCr image in n bits
% Modified by Elian Dib (elian.dib@inria.fr) on October, 18th 2018
function [ycbcr] = rgb2ycbcr(rgb,n,fullRange,conv2int)
% Recommendation ITU-R BT.709-6
M = [ 0.212600 0.715200 0.072200 ;
-0.114572 -0.385428 0.500000 ;
0.500000 -0.454153 -0.045847];
if (nargin < 2)
if isinteger(rgb)
[~,n] = utils.precision(class(rgb));
else
n = 0;
end
end
if (nargin < 3)
fullRange = true;
end
if (nargin < 4)
if isinteger(rgb)
conv2int = true;
else
conv2int = false;
end
end
rgb = double(rgb)./double(2^n-1);
if fullRange
offsetY = 0;
scaleY = 255;
offsetC = 128;
scaleC = 255;
else
offsetY = 16;
scaleY = 219;
offsetC = 128;
scaleC = 224;
end
ycbcr = reshape(double(rgb), [], 3) * M';
ycbcr(:,1) = (scaleY*ycbcr(:,1) + offsetY)*2^(n-8);
ycbcr(:,2:3) = (scaleC*ycbcr(:,2:3) + offsetC)*2^(n-8);
ycbcr = reshape(ycbcr, size(rgb));
if conv2int
if(n<=8)
ycbcr = uint8(ycbcr);
elseif (n<=16)
ycbcr = uint16(ycbcr);
elseif (n<=32)
ycbcr = uint32(ycbcr);
elseif (n<=64)
ycbcr = uint64(ycbcr);
else
print('invalid bit depth')
end
end
end
\ No newline at end of file
+function img = rgb2ycbcr(img,n,fullRange,conv2int)
+%RGB2YCBCR Summary of this function goes here
+% Detailed explanation goes here
+
+% Recommendation ITU-R BT.709-6
+M = [ 0.212600 0.715200 0.072200 ;
+ -0.114572 -0.385428 0.500000 ;
+ 0.500000 -0.454153 -0.045847];
+
+if (nargin < 2)
+ dr = diff(getrangefromclass(img));
+ n = log2(double(dr)+1);
+else
+ dr = double(2^n-1);
+end
+
+if (nargin < 3); fullRange = true; end
+if (nargin < 4); conv2int = isinteger(img); end
+
+if fullRange
+ scaleY = 255; offsetY = 0 ; scaleC = 255; offsetC = 128;
+else
+ scaleY = 219; offsetY = 16; scaleC = 224; offsetC = 128;
+end
+
+img = double(img);
+img = reshape( reshape( img,[],3 )*M' ,size(img));
+img(:,:,1) = (scaleY*img(:,:,1) + dr*offsetY)/255;
+img(:,:,2) = (scaleC*img(:,:,2) + dr*offsetC)/255;
+img(:,:,3) = (scaleC*img(:,:,3) + dr*offsetC)/255;
+
+if conv2int
+ if(n<=8)
+ img = uint8(img);
+ elseif (n<=16)
+ img = uint16(img);
+ elseif (n<=32)
+ img = uint32(img);
+ elseif (n<=64)
+ img = uint64(img);
+ else
+ print('invalid bit depth')
+ end
+end
+
+end
\ No newline at end of file
diff --git a/ycbcr2rgb.m b/ycbcr2rgb.m
index 6e08ab6..8e22c4b 100644
--- a/ycbcr2rgb.m
+++ b/ycbcr2rgb.m
@@ -1 +1,46 @@
-% Created by Elian Dib (elian.dib@inria.fr) on October, 18th 2018
function [rgb] = ycbcr2rgb(ycbcr,n,fullRange,conv2int)
% Recommendation ITU-R BT.709-6
M = [ 1.000000 0.000000 1.574800 ;
1.000000 -0.187350 -0.468130 ;
1.000000 1.855630 0.000000];
if (nargin < 2)
if isinteger(ycbcr)
[~,n] = utils.precision(class(ycbcr));
else
n = 0;
end
end
if (nargin < 3)
fullRange = true;
end
if (nargin < 4)
if isinteger(ycbcr)
conv2int = true;
else
conv2int = false;
end
end
if fullRange
offsetY = 0;
scaleY = 255;
offsetC = 128;
scaleC = 255;
else
offsetY = 16;
scaleY = 219;
offsetC = 128;
scaleC = 224;
end
sz = size(ycbcr);
ycbcr = double(ycbcr);
ycbcr = reshape(ycbcr, [], 3);
ycbcr(:,1) = (ycbcr(:,1) -offsetY*2^(n-8))/(scaleY*2^(n-8));
ycbcr(:,2:3) = (ycbcr(:,2:3)-offsetC*2^(n-8))/(scaleC*2^(n-8));
rgb = ycbcr * M';
rgb = reshape(rgb, sz);
if conv2int
rgb = (2^n-1)*rgb;
if(n<=8)
rgb = uint8(rgb);
elseif (n<=16)
rgb = uint16(rgb);
elseif (n<=32)
rgb = uint32(rgb);
elseif (n<=64)
rgb = uint64(rgb);
else
print('invalid bit depth')
end
end
end
\ No newline at end of file
+function img = ycbcr2rgb(img,n,fullRange,conv2int)
+%YCBCR2RGB Summary of this function goes here
+% Detailed explanation goes here
+
+% Recommendation ITU-R BT.709-6
+M = [ 1.000000 0.000000 1.574800 ;
+ 1.000000 -0.187350 -0.468130 ;
+ 1.000000 1.855630 0.000000];
+
+if (nargin < 2)
+ dr = diff(getrangefromclass(img));
+ n = log2(double(dr)+1);
+else
+ dr = double(2^n-1);
+end
+
+if (nargin < 3); fullRange = true; end
+if (nargin < 4); conv2int = isinteger(img); end
+
+if fullRange
+ scaleY = 255; offsetY = 0 ; scaleC = 255; offsetC = 128;
+else
+ scaleY = 219; offsetY = 16; scaleC = 224; offsetC = 128;
+end
+
+img = double(img);
+img(:,:,1) = (255*img(:,:,1)-dr*offsetY)/scaleY;
+img(:,:,2) = (255*img(:,:,2)-dr*offsetC)/scaleC;
+img(:,:,3) = (255*img(:,:,3)-dr*offsetC)/scaleC;
+img = reshape(reshape( img,[],3 )* M' ,size(img));
+
+if conv2int
+ if(n<=8)
+ img = uint8(img);
+ elseif (n<=16)
+ img = uint16(img);
+ elseif (n<=32)
+ img = uint32(img);
+ elseif (n<=64)
+ img = uint64(img);
+ else
+ print('invalid bit depth')
+ end
+end
+
+end
\ No newline at end of file
--
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