How to resize an image for face detection?

Hi all,

I'm still new in Image processing. I just want to know:

1) What is the actual size for face detection function?

2) How to resize the image?

Because i got the warning that mentioned "Image is too big to fit on screen; displaying at 25% "

This is the normal code to process the image:

faceDetector = vision.CascadeObjectDetector;

I = imread('detectface.jpg');

bboxes = step(faceDetector, I);

IFaces = insertObjectAnnotation(I, 'rectangle', bboxes, 'Face');

figure, imshow(IFaces), title('Detected faces');

Answer 1

[Anand]

The vision.CascadeObjectDetector does not rely on you providing an image at a particular size.

That warning is only related to the image display. It is indicating that the image is too big for your monitor, and so MATLAB is displaying the image at a smaller size. This does not affect the face detection.

If you find that the faces you're looking for are not being detected correctly, I would suggest playing around with the MinSize, MaxSize and ScaleFactor parameters.

[Ana]

Yeah. The current code do not detect the face correctly.

Answer 2

[Image Analyst]

I don't know what you mean by the size of a function . To get the size of an image, you can do

[rows, columns, numberOfColorChannels] = size(I);

though I recommend you not use I for the image variable. It looks too much like l (lower case "L") or 1 (the number).

You can resize an image with the imresize() function.

Answer 3

[Michael scheinfeild]

its better to resize all faces to same size like 128*64