How to view points in a high resolution image

Say I have a very large image, which I display using imagesc, since it has more points than pixels, the resulting image will lack details. If I have an image that is mostly 0s, and only 1 in a few points, the resampling that is done to change the image resolution will discard the desired points. The following code gives an example:

I = zeros(2000, 2000);
I(123,456) = 1;
imagesc(I);

Which results in:

Only after zooming in can I see the desired point:

I am not interested in solutions which include listing the points, such as using find, I am looking for visual solutions.

I have found that using rectangle draws something that can be seen in any zoom level, however I am looking for a solution that will work even for a large amount of points without using a work-intensive for loop. I am hoping for a solution that will also work for non-binary images, that does not require computing the down-sampling myself everytime the figure is resized.

Thanks!

Answer 1

[Gokul Nath S J]

Hi Yoad,

It seems that you are not able to identify where the peaks intensity occurs in an image which contains almost all the values as zero. I can provide some workaround for this issue.

1. You can directly open up the image matrix in MATLAB editor and look for values which are non-zero. It will be easy to idenify those values visually since the other points are zero.
2. For images which are non binary, it will be a nice idea to see the images in dB scale. You will easily understand those values which are having some significant intensities. For example, it is equite useful in scenerios where you can visualize frequency domain representation of a gray scale images.

For more information, kindly refer to the following example.

https://in.mathworks.com/matlabcentral/answers/261707-how-to-convert-an-image-to-frequency-domain-in-matlab

with regards,

Gokul Nath S J