Canon 或 FinePix ISO 图像的剪切是什么意思?
What does clipping at Canon or FinePix ISO image mean?
我正在尝试检查相机噪音。
我也参考如下 http://www.cs.tut.fi/~foi/
但是我想知道在下面的代码中剪裁是什么意思。
:代码
%% ====================================================================================================================================
%% LOAD BITMAP/RAW IMAGE % raw-data images which are loaded below can be downloaded from http://www.cs.tut.fi/~foi/sensornoise.html
%% ====================================================================================================================================
if 1 %% load "noise-free" image and add noise (OTHERWISE LOAD RAW DATA, SEE BELOW)
add_noise=1; % add noise to image
a=0.1^2; b=0.04^2; % noise parameters a,b
% a=0.1^2; b=0.02^2; % noise parameters a,b
% a=0.0^2; b=0.2^2; % noise parameters a,b
% a=(1/30); b=0.1^2; % noise parameters a,b
clipping_below=1; % on/off [keep off for pure-poissonian (no gaussian terms) noise, since there are no negative errors]
clipping_above=1; % on/off
prior_density=1; % type of prior density to use for ML (0)
% % 1: zero_one uniform prior density [0,1];
% y=im2double(imread('image_man1024.tiff'));
% y=im2double(imread('image_testpat1024.tiff'));
y=im2double(imread('y_piecewise.tif'));
% y=im2double(imread('y_piecewise_fibo.tif'));
else %% RAW %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
add_noise=0; %% DO NOT ADD NOISE TO RAW-DATA (IT HAS ENOUGH NOISE ALREADY! :) )
clipping_below=1; %%%% on off %% RAW-DATA IS ASSUMED TO BE CLIPPED FROM ABOVE AND BELOW
clipping_above=1; %%%% on off
prior_density=0; % type of prior density to use for ML (0)
% % 0: zero_infty uniform prior density (R+); (default, use this for raw-data)
一般来说,当一个值超过某个阈值并被迫达到该阈值时,就会发生削波。也称为饱和(意外时)、钳位(故意时)等。
这在数字系统(包括数码摄影)中很常见,您可以在其中使用具有指定位数的二进制值来表示某些数据。该二进制值然后具有由位数和它们用于编码值的方式暗示的上限和下限。
在这种情况下,代码似乎正在生成噪声以添加到图像中。没有引用产生噪音的表达式,但评论表明泊松分布,这是一个数学函数,可以产生超过图像动态范围的输出。 clipping_below
和 clipping_above
这两个标志是控制标志,允许用户指定是否应裁剪这些值,即限制为数据类型的上限和下限。
我正在尝试检查相机噪音。 我也参考如下 http://www.cs.tut.fi/~foi/
但是我想知道在下面的代码中剪裁是什么意思。
:代码
%% ====================================================================================================================================
%% LOAD BITMAP/RAW IMAGE % raw-data images which are loaded below can be downloaded from http://www.cs.tut.fi/~foi/sensornoise.html
%% ====================================================================================================================================
if 1 %% load "noise-free" image and add noise (OTHERWISE LOAD RAW DATA, SEE BELOW)
add_noise=1; % add noise to image
a=0.1^2; b=0.04^2; % noise parameters a,b
% a=0.1^2; b=0.02^2; % noise parameters a,b
% a=0.0^2; b=0.2^2; % noise parameters a,b
% a=(1/30); b=0.1^2; % noise parameters a,b
clipping_below=1; % on/off [keep off for pure-poissonian (no gaussian terms) noise, since there are no negative errors]
clipping_above=1; % on/off
prior_density=1; % type of prior density to use for ML (0)
% % 1: zero_one uniform prior density [0,1];
% y=im2double(imread('image_man1024.tiff'));
% y=im2double(imread('image_testpat1024.tiff'));
y=im2double(imread('y_piecewise.tif'));
% y=im2double(imread('y_piecewise_fibo.tif'));
else %% RAW %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
add_noise=0; %% DO NOT ADD NOISE TO RAW-DATA (IT HAS ENOUGH NOISE ALREADY! :) )
clipping_below=1; %%%% on off %% RAW-DATA IS ASSUMED TO BE CLIPPED FROM ABOVE AND BELOW
clipping_above=1; %%%% on off
prior_density=0; % type of prior density to use for ML (0)
% % 0: zero_infty uniform prior density (R+); (default, use this for raw-data)
一般来说,当一个值超过某个阈值并被迫达到该阈值时,就会发生削波。也称为饱和(意外时)、钳位(故意时)等。
这在数字系统(包括数码摄影)中很常见,您可以在其中使用具有指定位数的二进制值来表示某些数据。该二进制值然后具有由位数和它们用于编码值的方式暗示的上限和下限。
在这种情况下,代码似乎正在生成噪声以添加到图像中。没有引用产生噪音的表达式,但评论表明泊松分布,这是一个数学函数,可以产生超过图像动态范围的输出。 clipping_below
和 clipping_above
这两个标志是控制标志,允许用户指定是否应裁剪这些值,即限制为数据类型的上限和下限。