ppu-ocv/deskew.d.ts

A type-safe, modular, chainable image processing library built on top of OpenCV.js with a fluent API leveraging pipeline processing.

import type { CanvasLike } from "./canvas-factory.js";
/**
 * Options for configuring the deskew service
 */
export type DeskewOptions = {
    /**
     * Enable detailed logging of each processing step.
     * @default false
     */
    verbose?: boolean;
    /**
     * Remove detected boxes with area below this threshold, in pixels.
     * Used to filter out noise when detecting text regions.
     * @default 20
     */
    minimumAreaThreshold?: number;
};
/**
 * Service for calculating the skew angle of an image containing text.
 *
 * This service analyzes text regions in an image to determine its skew angle
 * using multiple methods (minAreaRect, baseline analysis, and Hough transform)
 * to robustly calculate the average text orientation.
 *
 * @example
 * ```ts
 * import { DeskewService } from 'ppu-ocv';
 *
 * const service = new DeskewService({ verbose: true });
 * const canvas = ...; // your canvas with text
 * const angle = await service.calculateSkewAngle(canvas);
 * console.log(`Skew angle: ${angle}°`);
 *
 * // Or deskew the image directly
 * const deskewed = await service.deskewImage(canvas);
 * ```
 */
export declare class DeskewService {
    private readonly verbose;
    private readonly minimumAreaThreshold;
    /**
     * Create a DeskewService.
     * @param options - Configuration. See {@link DeskewOptions}.
     */
    constructor(options?: DeskewOptions);
    private log;
    /**
     * Calculate the skew angle of text in a probability map or binary image.
     *
     * This method processes the input image to detect text regions and calculates
     * the average skew angle using multiple robust methods.
     *
     * @param canvas - Canvas containing a probability map or binary image of text regions
     * @returns The calculated skew angle in degrees (positive = clockwise, negative = counter-clockwise)
     */
    calculateSkewAngle(canvas: CanvasLike): Promise<number>;
    /**
     * Deskew an image by detecting its skew angle and rotating it.
     *
     * This is a convenience method that combines `calculateSkewAngle()`
     * with rotation to produce a straightened image.
     *
     * @param canvas - Canvas containing the image to deskew
     * @returns A new canvas with the deskewed image
     */
    deskewImage(canvas: CanvasLike): Promise<CanvasLike>;
}