Intel MediaSDK Lens distortion correction (using RAW accelerator) can’t get the same corrected image as PTGUI and Matlab

yue_c_ · ‎03-23-2017

Intel MediaSDK Lens distortion correction (using RAW accelerator) can’t get the same corrected image as PTGUI and Matlab,even using the same parameters: a b c d.

1.The meida_raw_accelerator_man.pdf describes the 3^rd degree polynomial for correcting lens distortion :

After doing some research and reading articles,we found the polynomial for correcting lens distortion should be:

2.We use polynomial as the correcting polynomial.

Set parameters value: a=0.0925 b=-0.2676 c=-0.0997c=1.2755

Source image: circle.bmp

PTGUI result: result_ptgui.bmp

Matlab result:result_matlab.bmp

MediaSDK result: result_mediasdk_0.bmp

Matlab code:untitle.m

close all; clear all; clc;

tic;
A = imread('circle.bmp');
img_gray = rgb2gray(A);
[m,n,k] = size(A);
P =[0.0925   -0.2676   -0.0997    1.2755];
C=[];

x0 = m/2;
y0 = n/2;
for u=1:m
    for v=1:n
        r = sqrt((u-x0)^2+(v-y0)^2);
        rt = polyval(P,r/x0)*r;
      
        if r ==0
            C(u,v,1)=A(x0,y0,1);
            C(u,v,2)=A(x0,y0,2);
            C(u,v,3)=A(x0,y0,3);         
        else 
            i = fix((u-x0)*rt/r)+x0;
             j = fix((v-y0)*rt/r)+y0;
            C(u,v,1)=A(i,j,1);
            C(u,v,2)=A(i,j,2);
            C(u,v,3)=A(i,j,3);
        end
    end
end
C = uint8(C);
imshow(C);

toc;

MediaSDK program: sample_camera_d.exe

MediaSDK command line:

sample_camera_d.exe -i bayer_circle.raw -f bggr -b 16 -w 4000 -h 3000 -lens 0.0925 -0.2676 -0.0997 1.2755 -o result_mediasdk_

PTGUI and Matlab can get the same result with the same params a,b,c and d. But the MediaSDK lens correction fails to get the same result under the same a b c d.

Now ,we call parameters of PTGUI and Matlab as a,b,c,d. The params of MediaSDK are a_mb_mc_md_m.we want to know that :

(1)we know the value of the params a b c and d, how to set the value of a_mb_mc_md_mto get the same corrected image as PTGUI and Matlab.

(2)What’s the relationship between a b c d and a_mb_mc_md_m

₍₃₎Does mediaSDK use polynomial ? If not,what is the mediaSDK polynomial for correcting.And how can we translate a b c d for quick correcting.

ps.does not the sample_camera.exe support the argb16 input format? the problem is described in the topic:

https://software.intel.com/en-us/forums/intel-media-sdk/topic/704495

yue_c_ · ‎03-23-2017

the source and destination image which is bmp format.And the bayer format of the source image .

543518

thanks.