CR-Vision Image Processing Cheat Sheet¶

This section is a quick overview of sample code for essential image processing operations using CR-Vision library. For more detailed code examples, please explore the examples directory in the source code.

The examples below freely use other image processing libraries like opencv, imageio, scikit-image wherever applicable along with the features provided by cr-vision.

Essential Imports:

import imageio
import cv2
from cr import vision

Image Read/Write¶

Reading image in BGR format:

image = cv2.imread(image_path)

Reading image in RGB format:

image = imageio.imread(image_path)

Color Space Conversion¶

From BGR to Gray Scale:

gray_image = vision.bgr_to_gray(image)

Resizing¶

Resizing operations preserve aspect ratio by default.

Resize to a specific height:

image = vision.resize_by_height(image, target_height)

Resize to a specific width:

image = vision.resize_by_width(image, target_width)

Resize an image if its width exceeds a given maximum width:

image = vision.resize_by_max_width(image, max_width)

Resize to a specific width and height (aspect ratio is not preserved):

image = vision.resize(image, target_width, target_height)

Thresholding¶

Adaptive Gaussian Thresholding on an image:

thresholded_image = vision.adaptive_threshold_gaussian(
    gray_image, block_size=115, constant=1)

Rotations¶

Rotate by a specific angle:

from cr.vision import geom
image = geom.rotate(image, angle)

Translations¶

Translate an image by (x,y) pixels:

from cr.vision import geom
image = geom.translate(image, (x, y))

Logos¶

Adding a logo in a corner:

from cr.vision.edits import logo
image = cv2.imread(image_path)
logo = cv2.imread(logo_path)
logo = cv2.resize(logo, (0, 0), fx=0.5, fy=0.5)
image = logo.add_logo(image, logo)

Borders¶

Add multiple borders of specific widths and colors:

from cr.vision import edits
image = edits.add_multiple_borders(image, widths=20, colors=[
    colors.BLUE, colors.RED, colors.GREEN])

Add a letterbox around an image:

from cr.vision import edits
image = edits.add_letter_box_pattern(image, letterbox_height)