MATLAB: How to increase number of rows and cols without changing the image size

digital image processingimage processingmatlab function

Is there a function to increase the number of rows and cols without changing the image size?

Example: I have an image that is 301X301 with pixel size 1mm. How do I increase the number of pixels to 1024X1024 with pixel size (301/1024)mm? Effectively maintaining the image size.

imresize only change the number of pixels, not pixel size. Am i right?

Best Answer

That's correct. How big you consider a pixel to be in "real world units" depends on the calibration you're using. It could be one micron, one kilometer, or one light year. If I have a length that is 1 meter long in MATLAB, and it happens to be 1000 pixels long, then I can multiply the number ob pixels by 1/1000 to get the distance in meters. If I resize the image so that that length is now 2000 pixels long, then my calibration factor will have to be 1/2000 now in order to still get a real world distance of one meter again.

Related Solutions

MATLAB: How to improve pixel resolution in an image

If you have a 951 wide image with 1 mm per pixel, then the field of view is 951 mm. Now if you reduce this to 512 pixels, the field of view is still the same - 951 mm - so the resolution is now 951 mm / 512 pixels = 1.86 mm per pixel.

If you want 250 mm, then you need to crop out a 250x250 mm chunk from the 951x951 image. So use imcrop to extract a rectangle of that size from the desired location. Once you've done that, you can resize from 250 by 250 pixels to 512 x 512 pixels. Your field of view will stay 250 mm since you are still looking at the same stuff, but it will just have a different image matrix size (512x512). The image may look softer since you are more than doubling the size of a fixed 250x250 mm subimage.

MATLAB: How to generate an image 512 pixels x 512 pixels with a square 50 pixels x 50 pixels located at the center

A=zeros(512);
A(232:281,232:281)=1;
a1=uint8(50*A+100);
a2=uint16(500*A+1000);
a3=single(...);

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Related Solutions

MATLAB: How to improve pixel resolution in an image

MATLAB: How to generate an image 512 pixels x 512 pixels with a square 50 pixels x 50 pixels located at the center

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