01 · THRESHOLD cv2.threshold
SOURCE
→
THRESHOLDED
THRESHOLD
128
MODE
02 · HISTOGRAM + EQUALIZATION
ORIGINAL
EQUALIZED
03 · MORPHOLOGY erode / dilate / open / close
BINARY IN
→
MORPHED
OPERATION
KERNEL
3×3
04 · CONTOURS cv2.findContours
EDGE THRESH
50
— contours
05 · COLOR SPACES RGB → HSV → LAB
RGB
HSV
LAB · L
GRAY
Different color spaces highlight different things. HSV separates hue from brightness. LAB is perceptually uniform.
06 · GEOMETRIC rotate · scale · translate · perspective
ROTATE
0°
SCALE
1.00
SKEW
0
07 · MASKING circular ROI
RADIUS
80
FEATHER
15
08 · EDGE DETECTION Sobel / Canny
METHOD
// 02
Source · pick the image driving all operations above
Pre-deep-learning → Every face-detector, license-plate reader, and document scanner up until ~2014 was built from operations like these. CNNs absorbed most of the workload, but classical CV is still the fastest, most predictable preprocessing layer in any vision system.