CvImage

CvImage is a chainable wrapper for OpenCV's python bindings. This jQuery-like syntax is convenient for performing series of filters and transformations on a single image.

Usage

• Install from pip (pip install cvimage) or [GitHub releases] All cv2 methods that take an image (numpy array) as their first argument can be called from a CvImage context. Any of those methods that return an image can be chained together. cv2 constants can be passed as strings.

from cvimage import CvImage

im = CvImage('test.png') \
	.blur(3) \
	.threshold(0, 100, 'THRESH_BINARY') \
	.canny(100, 200) \
	.save('test-edges.png')

A CvImage instance can be created with both a pre-existing image (numpy array) or with a filename, which gets passed to cv2.imread. An image can be saved at any time using CvImage.save(filename), which calls cv2.imwrite.

Method names beginning with a Capital Letter (e.g. Canny, Sobel, Laplacian) are normalized to lowercase (canny, sobel, laplacian). On the one hand, they are names of people, on the other hand, it causes an inconsistent API.

Methods that return data as well as an image, such as cv2.threshold, save their data to CvImage.data - if they are chained together, only the last called method's data is retained.

result, threshold = cv2.threshold(src_im, 100, 200, cv2.THRESH_BINARY)
im = CvImage(src_im).threshold(100, 200, cv2.THRESH_BINARY)
# im.data == result

Reference

CvImage(...)

Main class that wraps cv2 methods. Constructor will create a new CvImage from any of the following:

• OpenCV-compatible image data (numpy.ndarray)
• Filename to pass to cv2.imread
• A previously created CvImage to copy

Attributes

name	type	description
height	int	image height
width	int	image width
depth	int	image depth
image	numpy.ndarray	image data
data	var	temporary data returned from wrapped functions

Methods

name	description
show([name])	wraps cv2.imshow
save([filename])	wraps cv2.imwrite
copy()	returns a new CvImage with the same data
wait([delay])	wraps cv2.waitKey
preview([delay])	calls both show() and wait(delay)
crop(pt1, pt2)	slices the image, cropping from. Accepts floats as a percentage of the image size.
findContours(...)	wraps cv2.findContours in a non-destructive way

CvContour(contour)

cvKernel()

Changelog

0.1.1

• Added constant passing by string, with hinted namespaces (e.g. threshold(...,'binary') resolves to threshold(...,cv2.THRESH_BINARY))