Overview

The opencv package provides PascalAI bindings to OpenCV, the world's most popular computer vision library. It covers image I/O, geometric transforms, filters, edge and face detection, drawing primitives, and basic video capture.

Quick Start

uses opencv;

var img := LoadImage('/photos/portrait.jpg');
var w, h: Integer;
ImageSize(img, w, h);
WriteLn('Size: ', w, 'x', h);

// Resize and detect faces
var thumb := FitImage(img, 640);
var result := DrawFaces(thumb);
SaveImage('/out/annotated.jpg', result);

FreeImage(img);
FreeImage(thumb);
FreeImage(result);

Image I/O

var img := LoadImage('/path/to/photo.jpg');  // PNG, JPG, BMP, TIFF...
SaveImage('/path/to/out.png', img);
var b64 := ImageToBase64(img);              // data URI ready
var w, h: Integer;
ImageSize(img, w, h);
FreeImage(img);                             // always release

Transforms

var resized  := Resize(img, 800, 600);
var cropped  := Crop(img, 10, 10, 200, 200);
var rotated  := Rotate(img, 45.0);         // degrees
var flipped  := Flip(img, 1);              // 1=horizontal
var gray     := ToGrayscale(img);
var fit      := FitImage(img, 512);        // longest edge = 512

Filters

var blurred  := Blur(img, 5);              // kernel size (odd)
var smooth   := GaussianBlur(img, 7, 1.5);
var sharp    := Sharpen(img, 1.2);
var bright   := AdjustBrightnessContrast(img, 30, 1.2);

Detection

// Canny edge detection
var edges := EdgeDetect(img, 50.0, 150.0);
SaveImage('/out/edges.png', edges);

// Face detection
var faces := FaceDetect(img);
WriteLn(Length(faces), ' face(s) found');
var annotated := DrawFaces(img);

// Hough circle detection
var circles := DetectCircles(img, 20, 200);

Drawing

var Red   := RGB(255, 0, 0);
var Green := RGB(0, 255, 0);
var Blue  := RGB(0, 0, 255);

DrawRect(img,   10, 10, 100, 50, Red,  2);   // x,y,w,h
DrawCircle(img, 200, 200, 40, Green, 2);
DrawLine(img,   0, 0, 400, 300, Blue, 1);
DrawText(img, 'Hello!', 20, 40, RGB(255,255,255), 1.5);

Video

var cap := VideoOpen('0');          // '0' = webcam; or path to .mp4
var fps := VideoGet(cap, 'fps');
WriteLn('FPS: ', fps:0:1);

var frame := VideoRead(cap);
while frame <> nil do begin
  var gray := ToGrayscale(frame);
  SaveImage('/tmp/frame.jpg', gray);
  FreeImage(frame);
  FreeImage(gray);
  frame := VideoRead(cap);
end;

VideoClose(cap);