I want to rectify a stereo image pair in MATLAB. To rectify, I use the following call:
[J1,J2] = rectifyStereoImages(I1,I2, cameraParamsStereo);
If I do this, then I only get the so called valid part of each image which is smaller than the initial image size. If I specify the argument OutputView as full, then I get rectified images which are larger than the original ones.
Is there a way to get rectified images that have the same size as the original ones?
It is possible in principle, but rectifyStereoImages does not support this.
Related
I am using a dataset which provides depth images of human, I need to extract the object from this image or at least remove the other distortion in the image that not belong to the human body In Matlab.
a sample of images is shown below:
This is the output when I used
I = imread ('39.jpg');
human = sum(I,3)>10+10;
human
Any way to do that please?
thanks in Advance
For the image you show, where everything is grayscale but something is red, then just do:
so=imread('https://i.stack.imgur.com/hZOQv.jpg');
human=sum(abs(diff(single(so),1,3)),3)>20;
This essentially compares the difference in RGB values of the pixels, and gets the one above a threshold. If you have proper pngs, then the threshold should just be 1, however with jpg artifacts you may need a higher value, for this image 20 does the job.
There are some tiny artefacts in the result image, very likely due to jpg. When you do science, you need to store in png. If you have absolutely no other choice than jpg, then you may have artefacts.
I am currently recording on a single camera the images, one aside of the other one, of the same sample out of a microscope.
I have 2 issues with that, and I figured out that in post procesing with Matlab I could arrange these questions.
-First, the 2 images on the camera are supposed to have the same pixel size, or one is just a litle bigger than the other one, probably because of optical pathways. What is the adapted Matlab function or way to correlate the two images so they will have exactly the same pixel size in X and Y ?
Two images on same camera , one bigger or smaller compared to the other one
-Secondly, my sample is moving a litle during the recording ( while still staying in my field of view of course ). To make my analysis easier, it would be suitable that I could correct the images so the sample remain at the same place as in the first image, to perform calculations on it easier. What would be the adapted Matlab function or way to correct this movement in the image ?
Sample moving in the image on the camera
Sorry for the poor quality of my drawings !
Thank you very much for your advices and help.
First zero-pad the images to a sufficient degree, to get them both to double the size of the bigger one.
size_padding = max(size(fig1),size(fig2));
fig1_pad = padarray(fig1,size_padding-size(fig1),'post');
fig2_pad = padarray(fig2,size_padding-size(fig2),'post');
Assuming the sample is the only feature present in the images, the best way to proceed would be to use the xcorr2() function and find the lag corresponding to the maximum correlation, to get the space shift between the two images:
xc = xcorr2(fig1_pad,fig2_pad);
[max_cc, imax] = max(abs(xc(:)));
[ypeak, xpeak] = ind2sub(size(xc),imax(1));
corr_offset = [ (ypeak-size(fig2_pad,1)) (xpeak-size(fig2_pad,2)) ];
You then use circshift() to shift one of the images using the lag you obtained in the last step.
fig2_shift = circshift(fig2_pad,corr_offset);
You now have two images of the same size, where hopefully the sample is in the same position. If you want to remove the padding zeroes, crop the images to your liking with respect to the center using imcrop().
I have an gray scale image of size <2559x3105 uint16>. when I try to open this image, I get warning that it is too big. I have tried imresize() function to make it small<512x512 uint8> in size. When I plot the original image and re-sized image, the intensity gets decreased after re-sizing. I want to re-size original image without changing in its pixel values. Is there any solution?
If you would like to keep your final image as uint8, I think you would be needed to first convert the uint16 image to uint8 image using im2uint8 -
uint8_image = im2uint8(uint16_image);
Then you may apply imresize on uint8_image.
But, if you don't want your final image to be of uint8 type, you can directly use imresize and it would keep the datatype, i.e. the resized image would be of uint16 type.
Read the docs and use the nearest neighbor method. That is,
resized = imresize(original, scale, 'nearest')
This will not use interpolated values. The downside is of course that edges might be jagged.
It sounds like your 16-bit image uses linear codes while the resulting 8-bit image needs to be gamma corrected. If this is the case you can use imadjust with a gamma parameter of 1/2.2 to produce the brighter image.
Do you get the warning when you display it with imshow? Does it say something like "Image to large to fit the screen, resizing to xx%"? If so, then you can simply ignore the warning. Otherwise, you can can set the 'InitialMagnification' parameter of imshow to resize the figure, but not the image itself.
I'd like to resize the components contained in a 3D binary image sequence without changing any of the dimensions of the sequence itself.
I'm not sure if I need to do it on a component-by-component basis, if yes, then how do I create a transform such that the resized components are re-positioned 'correctly' in the image sequence? By 'correctly', I mean with the same centre of mass as the original unprocessed components.
(If that last paragraph doesn't make sense then please ignore)
A 2D example: suppose I wanted to enlarge by 10% the white blobs in the following [295x445] image
How would you do this without making the image itself larger?
you could use the imdilate function to dilate the regions of interest. The examples in the webpage show how to use this function.
I want to read a .fits image of wide field sky and display the RGB values contained in a star. Can you please suggest a method to do so?
I have used fitsread to read in the image but i am not able to show the RGB values for specific locations(star).
In order to do this, you'll need a proper rgb fits file. The only .fits viewer I know of, ds9, does not support saving rgb fits files, but rather as the three separate (r,g,b) fits images. You can use "getpix" from wcstools (http://tdc-www.harvard.edu/wcstools/) or scisoft (http://www.eso.org/sci/software/scisoft/) on the individual frames. Note that "getpix" returns the pixel value given an image (x,y) location. ds9 does not provide the physical image location, but rather the wcs coordinates, so you may have to convert to image coordinates before calling getpix.