center crop image based on other image dimension

Question

stav marzuk 2022-5-2

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1710095-center-crop-image-based-on-other-image-dimension

评论： stav marzuk 2022-5-4

Hi,

I have two images of the same area but with different size: an RGB and TIR format.

I'm drawing a polygon on one of them and convert it to a mask in order to get the same cropped area in the second image.

in QGIS it works: (this is the TIR on top of the RGB)

When I try to do it in MATLAB it fails.

The polygon-

To use the mask in the RGB image I resized the image in the center:

targetSize = size(TIR);
r = centerCropWindow2d(size(RGB),targetSize);
RGB = imcrop(RGB,r);

Now when I try to use the same mask on the RGB image, I get a different area (much closer):

I've also tried to do it the other way, to padd the small image with zeros around it accordingly.

Is it even possible? I want to get the same output as in the QGIS.

Any help is highly appreciated!

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stav marzuk 2022-5-4

在 MATLAB Online 中打开

Thank you so much for the response.

I'm not using imref2d(), here is my code:

%----------------tir image 
TIR=imread("path.tif");
tfw_file=strcat("pathR.tfw");
tfw=worldfileread(tfw_file,'planar',size(TIR));
TIR= double(TIR);
TIR(find(TIR<0.1))=0;
TIR(find(TIR>70))=0;
%----------------rgb image 
RGB=imread("Path.tif");
tfw_file_RGB=strcat("path.tfw");
tfw_RGB=worldfileread(tfw_file_RGB,'planar',size(RGB));
RGB= double(RGB(:,:,2));
% --------- draw polygon and make mask
[hp,Y_upper_pix,Y_lower_pix,X_upper_pix,X_lower_pix,X_upper_map,Y_upper_map,X_lower_map,Y_lower_map]=trim_tif(TIR,tfw);
BW=createMask(hp);
% ------------ trim rgb and tir and tfw approximatly 
trim_tfw =worldfileread([tif_PathName '.tfw']);
trim_tfw(3,1)=X_upper_map;
trim_tfw(3,2)=Y_upper_map;
tif_mask=TIR.*BW;
tif_mask=tif_mask(Y_upper_pix:Y_lower_pix,X_upper_pix:X_lower_pix,:);
tif_mask_RGB=RGB.*BW;
tif_mask_RGB=tif_mask_RGB(Y_upper_pix:Y_lower_pix,X_upper_pix:X_lower_pix,:);

if there is anything more I can provide, let me know and thanks again!!

DGM 2022-5-4

I am really not familiar with mapping toolbox stuff at all, but maybe someone else is. I might be able to bang my head against it for a bit, but I'd really have to have the actual files to be able to have any confidence that I'm actually replicating the issue correctly.

Is trim_tif() a user-defined function?

stav marzuk 2022-5-4

在 MATLAB Online 中打开

The mapping toolbox stuff is not a problem, I only need help with cropping the same part from both images (RGB AND TIR).

trim_tif() :

function [hp,Y_upper_pix,Y_lower_pix,X_upper_pix,X_lower_pix,X_upper_map,Y_upper_map,X_lower_map,Y_lower_map]=trim_tif(RGB,tfw)
% trim tif image
h=figure;
mapshow(uint8(RGB),tfw);
xlim(tfw.XLimWorld);ylim(tfw.YLimWorld);
hold on
figure(h);
hp = drawpolygon;
pos_map=hp.Position;
[row_pos_pix,col_pos_pix]=map2pix(tfw,pos_map);
X_upper_pix=round(min(col_pos_pix));
Y_upper_pix=round(min(row_pos_pix));
X_lower_pix=round(max(col_pos_pix));
Y_lower_pix=round(max(row_pos_pix));
[X_upper_map,Y_upper_map]=pix2map(tfw,Y_upper_pix,X_upper_pix);
[X_lower_map,Y_lower_map]=pix2map(tfw,Y_lower_pix,X_lower_pix);
end

The problem is when i upload the images to matlab, their size is really diffrent and the location is not the same. I'm looking for a way to cut an area from one picture and get the same area in the same size from the second one as well.

Here is a link to the images I try to use:

https://drive.google.com/drive/folders/1Qwim4HoBWFygA_xswt_x2XajhH9KGq7D?usp=sharing

Thanks again :)

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center crop image based on other image dimension

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center crop image based on other image dimension

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