How to Resize Image?

OpenMV Products
#1

I’m using the Cam H7 to identify objects that fill the field of view of the sensor. When training an ML algorithm, the training images are resized. I have not seen a method in OpenMV for resizing images (for example resize from QVGA 320x240 to 64x64).

A work-around I came up with is to use an extra_fb and combine the zoom of img.rotation_corr with a crop in img.copy.

extra_fb = sensor.alloc_extra_fb(64,64,sensor.GRAYSCALE)
img = sensor.snapshot()

resize to (88x66) = (320x240) * 0.275, resized image starts at x=116, y = 87

img.rotation_corr(zoom=0.275)

crop middle 64x64

roi_copy = (128,88,64,64)
extra_fb = img.copy(roi=roi_copy)

Is there a better way to do a resize in OpenMV?

Thanks

#2

https://docs.openmv.io/library/omv.image.html?highlight=crop#image.image.crop

There’s an x/y scale.

Also, if you are using the latest firmware not yet released we have a new bicubic and bilinear scaling pipeline integrated into draw_image. copy/crop/etc will be updated to use it.

#3

You can also crop the images captured by the sensor by using set_windowing:

https://docs.openmv.io/library/omv.sensor.html#sensor.sensor.set_windowing