east.py

import cv2
import depthai
import numpy as np

_conf_threshold = 0.5

def get_cv_rotated_rect(bbox, angle):
    x0, y0, x1, y1 = bbox
    width = abs(x0 - x1)
    height = abs(y0 - y1)
    x = x0 + width * 0.5
    y = y0 + height * 0.5
    return ([x.tolist(), y.tolist()], [width.tolist(), height.tolist()], np.rad2deg(angle))

def rotated_Rectangle(bbox, angle):
    X0, Y0, X1, Y1 = bbox
    width = abs(X0 - X1)
    height = abs(Y0 - Y1)
    x = int(X0 + width * 0.5)
    y = int(Y0 + height * 0.5)

    pt1_1 = (int(x + width / 2), int(y + height / 2))
    pt2_1 = (int(x + width / 2), int(y - height / 2))
    pt3_1 = (int(x - width / 2), int(y - height / 2))
    pt4_1 = (int(x - width / 2), int(y + height / 2))

    t = np.array([[np.cos(angle), -np.sin(angle), x - x * np.cos(angle) + y * np.sin(angle)],
                  [np.sin(angle), np.cos(angle), y - x * np.sin(angle) - y * np.cos(angle)],
                  [0, 0, 1]])

    tmp_pt1_1 = np.array([[pt1_1[0]], [pt1_1[1]], [1]])
    tmp_pt1_2 = np.dot(t, tmp_pt1_1)
    pt1_2 = (int(tmp_pt1_2[0][0]), int(tmp_pt1_2[1][0]))

    tmp_pt2_1 = np.array([[pt2_1[0]], [pt2_1[1]], [1]])
    tmp_pt2_2 = np.dot(t, tmp_pt2_1)
    pt2_2 = (int(tmp_pt2_2[0][0]), int(tmp_pt2_2[1][0]))

    tmp_pt3_1 = np.array([[pt3_1[0]], [pt3_1[1]], [1]])
    tmp_pt3_2 = np.dot(t, tmp_pt3_1)
    pt3_2 = (int(tmp_pt3_2[0][0]), int(tmp_pt3_2[1][0]))

    tmp_pt4_1 = np.array([[pt4_1[0]], [pt4_1[1]], [1]])
    tmp_pt4_2 = np.dot(t, tmp_pt4_1)
    pt4_2 = (int(tmp_pt4_2[0][0]), int(tmp_pt4_2[1][0]))

    points = np.array([pt1_2, pt2_2, pt3_2, pt4_2])

    return points


def non_max_suppression(boxes, probs=None, angles=None, overlapThresh=0.3):
    # if there are no boxes, return an empty list
    if len(boxes) == 0:
        return [], []

    # if the bounding boxes are integers, convert them to floats -- this
    # is important since we'll be doing a bunch of divisions
    if boxes.dtype.kind == "i":
        boxes = boxes.astype("float")

    # initialize the list of picked indexes
    pick = []

    # grab the coordinates of the bounding boxes
    x1 = boxes[:, 0]
    y1 = boxes[:, 1]
    x2 = boxes[:, 2]
    y2 = boxes[:, 3]

    # compute the area of the bounding boxes and grab the indexes to sort
    # (in the case that no probabilities are provided, simply sort on the bottom-left y-coordinate)
    area = (x2 - x1 + 1) * (y2 - y1 + 1)
    idxs = y2

    # if probabilities are provided, sort on them instead
    if probs is not None:
        idxs = probs

    # sort the indexes
    idxs = np.argsort(idxs)

    # keep looping while some indexes still remain in the indexes list
    while len(idxs) > 0:
        # grab the last index in the indexes list and add the index value to the list of picked indexes
        last = len(idxs) - 1
        i = idxs[last]
        pick.append(i)

        # find the largest (x, y) coordinates for the start of the bounding box and the smallest (x, y) coordinates for the end of the bounding box
        xx1 = np.maximum(x1[i], x1[idxs[:last]])
        yy1 = np.maximum(y1[i], y1[idxs[:last]])
        xx2 = np.minimum(x2[i], x2[idxs[:last]])
        yy2 = np.minimum(y2[i], y2[idxs[:last]])

        # compute the width and height of the bounding box
        w = np.maximum(0, xx2 - xx1 + 1)
        h = np.maximum(0, yy2 - yy1 + 1)

        # compute the ratio of overlap
        overlap = (w * h) / area[idxs[:last]]

        # delete all indexes from the index list that have overlap greater than the provided overlap threshold
        idxs = np.delete(idxs, np.concatenate(([last], np.where(overlap > overlapThresh)[0])))

    # return only the bounding boxes that were picked
    return boxes[pick].astype("int"), angles[pick]


def decode_predictions(scores, geometry1, geometry2):
    # grab the number of rows and columns from the scores volume, then
    # initialize our set of bounding box rectangles and corresponding
    # confidence scores
    (numRows, numCols) = scores.shape[2:4]
    rects = []
    confidences = []
    angles = []

    # loop over the number of rows
    for y in range(0, numRows):
        # extract the scores (probabilities), followed by the
        # geometrical data used to derive potential bounding box
        # coordinates that surround text
        scoresData = scores[0, 0, y]
        xData0 = geometry1[0, 0, y]
        xData1 = geometry1[0, 1, y]
        xData2 = geometry1[0, 2, y]
        xData3 = geometry1[0, 3, y]
        anglesData = geometry2[0, 0, y]

        # loop over the number of columns
        for x in range(0, numCols):
            # if our score does not have sufficient probability,
            # ignore it
            if scoresData[x] < _conf_threshold:
                continue

            # compute the offset factor as our resulting feature
            # maps will be 4x smaller than the input image
            (offsetX, offsetY) = (x * 4.0, y * 4.0)

            # extract the rotation angle for the prediction and
            # then compute the sin and cosine
            angle = anglesData[x]
            cos = np.cos(angle)
            sin = np.sin(angle)

            # use the geometry volume to derive the width and height
            # of the bounding box
            h = xData0[x] + xData2[x]
            w = xData1[x] + xData3[x]

            # compute both the starting and ending (x, y)-coordinates
            # for the text prediction bounding box
            endX = int(offsetX + (cos * xData1[x]) + (sin * xData2[x]))
            endY = int(offsetY - (sin * xData1[x]) + (cos * xData2[x]))
            startX = int(endX - w)
            startY = int(endY - h)

            # add the bounding box coordinates and probability score
            # to our respective lists
            rects.append((startX, startY, endX, endY))
            confidences.append(scoresData[x])
            angles.append(angle)

    # return a tuple of the bounding boxes and associated confidences
    return (rects, confidences, angles)


def decode_east(nnet_packet, **kwargs):
    scores = nnet_packet.get_tensor(0)
    geometry1 = nnet_packet.get_tensor(1)
    geometry2 = nnet_packet.get_tensor(2)
    bboxes, confs, angles = decode_predictions(scores, geometry1, geometry2
                                               )
    boxes, angles = non_max_suppression(np.array(bboxes), probs=confs, angles=np.array(angles))
    boxesangles = (boxes, angles)
    return boxesangles


def show_east(boxesangles, frame, **kwargs):
    bboxes = boxesangles[0]
    angles = boxesangles[1]
    for ((X0, Y0, X1, Y1), angle) in zip(bboxes, angles):
        width = abs(X0 - X1)
        height = abs(Y0 - Y1)
        cX = int(X0 + width * 0.5)
        cY = int(Y0 + height * 0.5)

        rotRect = ((cX, cY), ((X1 - X0), (Y1 - Y0)), angle * (-1))
        points = rotated_Rectangle(frame, rotRect, color=(255, 0, 0), thickness=1)
        cv2.polylines(frame, [points], isClosed=True, color=(255, 0, 0), thickness=1, lineType=cv2.LINE_8)

    return frame


def order_points(pts):
    rect = np.zeros((4, 2), dtype="float32")
    s = pts.sum(axis=1)
    rect[0] = pts[np.argmin(s)]
    rect[2] = pts[np.argmax(s)]
    diff = np.diff(pts, axis=1)
    rect[1] = pts[np.argmin(diff)]
    rect[3] = pts[np.argmax(diff)]
    return rect


def four_point_transform(image, pts):
    rect = order_points(pts)
    (tl, tr, br, bl) = rect

    widthA = np.sqrt(((br[0] - bl[0]) ** 2) + ((br[1] - bl[1]) ** 2))
    widthB = np.sqrt(((tr[0] - tl[0]) ** 2) + ((tr[1] - tl[1]) ** 2))
    maxWidth = max(int(widthA), int(widthB))

    heightA = np.sqrt(((tr[0] - br[0]) ** 2) + ((tr[1] - br[1]) ** 2))
    heightB = np.sqrt(((tl[0] - bl[0]) ** 2) + ((tl[1] - bl[1]) ** 2))
    maxHeight = max(int(heightA), int(heightB))

    dst = np.array([
        [0, 0],
        [maxWidth - 1, 0],
        [maxWidth - 1, maxHeight - 1],
        [0, maxHeight - 1]], dtype="float32")

    M = cv2.getPerspectiveTransform(rect, dst)
    warped = cv2.warpPerspective(image, M, (maxWidth, maxHeight))

    return warped