Added hsv_picker.sh script to support cv template (#1102)

* Added hsv_picker.sh script to support cv template
- this allow a user to select an area on an image
  and sample the low and high HSV value to create
  a mask, like is used in the cv_control template.
- hsv_picker.sh script support picking from an image file
  or a video camera

scripts/hsv_picker.py

@@ -0,0 +1,283 @@
+#
+# Python/opencv script to show an image and then mask it 
+# using  low and high HSV values chosen with trackbars
+# or sampled from a rectangular select.
+# - click on a pixel to show it's position, RGB and HSV values
+# - select an area to sample low and high HSV value for an image mask OR
+# - adjust the trackbars to choose low and high HSV values for an image mask
+# - press Escape to reset the low and high hsv value
+# - press 'q' to quit
+#
+import cv2
+import numpy as np
+
+
+
+def nothing(x):
+    """
+    Trackbar callback does nothing
+    """
+    pass
+
+
+# 
+# Text metrics
+#
+font = cv2.FONT_HERSHEY_SIMPLEX
+line_height = 25  
+fontScale = 0.4
+text_color = (0, 0, 0)
+text_lines = []
+
+frame = None  # the current image frame
+
+def show_pixel_values(image, x, y):
+    """
+    Create text lines that show the value of the given pixel
+    The text lines are used in the main loop to draw text.
+    """
+    text = []
+    if image is not None:
+        text.append(f"Pixel at x={x}, y={y}")
+
+        colorsRGB = image[y,x]
+        text.append(f"Pixel RGB = ({colorsRGB[0]}, {colorsRGB[1]}, {colorsRGB[2]})")
+
+        colorsHSV = bgr_to_hsv(colorsRGB)
+        text.append(f"Pixel HSV = ({colorsHSV[0]}, {colorsHSV[1]}, {colorsHSV[2]})")
+
+        hsv_low, hsv_high = get_hsv_trackbars()
+        if hsv_low is not None and hsv_high is not None:
+            text.append(f"Mask HSV Low = ({hsv_low[0]}, {hsv_low[1]}, {hsv_low[2]})")
+            text.append(f"Mask HSV High = ({hsv_high[0]}, {hsv_high[1]}, {hsv_high[2]})")
+
+    return text
+
+
+def get_hsv_range(image, left, top, right, bottom):
+    if image is None:
+        return ((0, 0, 0), (179, 255, 255   ))
+
+    min_pixel = None
+    max_pixel = None
+    width = abs(right - left)
+    height = abs(bottom - top)
+    if width > 1 and height > 1:
+        #
+        # get min and max HSV values and put them into the trackbars
+        #
+        left = min(left, right)
+        right = left + width
+        top = min(top, bottom)
+        bottom = top + height
+
+        for y in range(top, bottom):
+            for x in range(left, right):
+                pixel = bgr_to_hsv(image[y, x])
+                if pixel[0] > 0:  # reject black noise pixels
+                    min_pixel = pixel if min_pixel is None else np.minimum(pixel, min_pixel)
+                    max_pixel = pixel if max_pixel is None else np.maximum(pixel, max_pixel)
+
+    return (min_pixel, max_pixel)
+
+
+# mouse callback variables
+drag_rect = None
+
+# mouse callback function
+def mouse_callback(event, x, y, flags, param):
+    global drag_rect, frame, text_lines
+
+    if frame is None:
+        return
+
+    if event == cv2.EVENT_LBUTTONDOWN: #checks mouse left button down condition
+        drag_rect = (x, y, x, y)
+        text_lines = show_pixel_values(frame, x, y)
+    elif event == cv2.EVENT_MOUSEMOVE:
+        if drag_rect is not None:
+            drag_rect = (drag_rect[0], drag_rect[1], x, y)
+            text_lines = show_pixel_values(frame, x, y)
+    elif event == cv2.EVENT_LBUTTONUP:
+        if drag_rect is not None:
+            width = abs(drag_rect[2] - drag_rect[0])
+            height = abs(drag_rect[3] - drag_rect[1])
+            if width > 1 and height > 1:
+                min_hsv, max_hsv = get_hsv_range(frame, *drag_rect)
+                if min_hsv is not None and max_hsv is not None:
+                    set_hsv_trackbars(min_hsv, max_hsv)
+            text_lines = show_pixel_values(frame, x, y)
+        drag_rect = None
+
+
+def set_hsv_trackbars(hsv_low, hsv_high):
+    global window_name
+    if hsv_low is not None and hsv_high is not None:
+        cv2.setTrackbarPos("h-low", window_name, hsv_low[0])
+        cv2.setTrackbarPos("s-low", window_name, hsv_low[1])
+        cv2.setTrackbarPos("v-low", window_name, hsv_low[2])
+        cv2.setTrackbarPos("h-high", window_name, hsv_high[0])
+        cv2.setTrackbarPos("s-high", window_name, hsv_high[1])
+        cv2.setTrackbarPos("v-high", window_name, hsv_high[2])
+
+
+def get_hsv_trackbars():
+    global window_name
+    h_low = cv2.getTrackbarPos('h-low', window_name)
+    s_low = cv2.getTrackbarPos('s-low', window_name)
+    v_low = cv2.getTrackbarPos('v-low', window_name)
+    h_high = cv2.getTrackbarPos('h-high', window_name)
+    s_high = cv2.getTrackbarPos('s-high', window_name)
+    v_high = cv2.getTrackbarPos('v-high', window_name)
+    return [h_low, s_low, v_low], [h_high, s_high, v_high]
+
+def print_hsv_trackbars():
+    (h_low, s_low, v_low), (h_high, s_high, v_high) = get_hsv_trackbars()
+    print(f"Low HSV  = ({h_low}, {s_low}, {v_low})")
+    print(f"High HSV = ({h_high}, {s_high}, {v_high})")
+
+def bgr_to_hsv(pixelRGB):
+    """
+    Convert a single RGB pixel to HSV
+    """
+    imgRGB = np.uint8([[pixelRGB]])  
+    imgHSV = cv2.cvtColor(imgRGB, cv2.COLOR_BGR2HSV)
+    pixelHSV = imgHSV[0][0]
+    return pixelHSV
+
+# Creating a window for later use
+window_name = 'hsv_range_picker'
+
+def main(camera_index=0, width=640, height=480, file_image=None):
+    global frame, drag_rect, text_lines
+
+    cap = None
+    if file_image is None:
+        cap = cv2.VideoCapture(camera_index)
+        cap.set(cv2.CAP_PROP_FRAME_WIDTH, width)
+        cap.set(cv2.CAP_PROP_FRAME_HEIGHT, height)
+
+    cv2.namedWindow(window_name)
+
+    # Starting with 100's to prevent error while masking
+    h,s,v = 100,255,255
+
+    # Creating track bar for hsv-low value
+    cv2.createTrackbar('h-low', window_name, 0, 179, nothing)
+    cv2.createTrackbar('s-low', window_name, 0, 255, nothing)
+    cv2.createTrackbar('v-low', window_name, 0, 255, nothing)
+
+    # trackbar for hsv high value
+    cv2.createTrackbar('h-high', window_name, 179, 179, nothing)
+    cv2.createTrackbar('s-high', window_name, 255, 255, nothing)
+    cv2.createTrackbar('v-high', window_name, 255, 255, nothing)
+
+    cv2.setMouseCallback(window_name, mouse_callback)
+
+    while(1):
+
+        frame = None
+        if file_image is not None:
+            frame = file_image.copy()
+        else: 
+            _, frame = cap.read()
+            if frame is None:
+                continue
+
+        #
+        # mask the image using the current HSV value
+        #
+
+        #converting to HSV
+        hsv = cv2.cvtColor(frame, cv2.COLOR_BGR2HSV)
+
+        # get info from track bar, create mask and mask the image
+        hsv_low, hsv_high = get_hsv_trackbars()
+
+        # Normal masking algorithm
+        hsv_low = np.array(hsv_low)
+        hsv_high = np.array(hsv_high)
+        mask = cv2.inRange(hsv, hsv_low, hsv_high)
+        image = cv2.bitwise_and(frame, frame, mask = mask)
+
+        # draw drag rectangle
+        if drag_rect is not None:
+            top_left = (min(drag_rect[0], drag_rect[2]), min(drag_rect[1], drag_rect[3]))
+            bottom_right = (max(drag_rect[0], drag_rect[2]), max(drag_rect[1], drag_rect[3]))
+
+            # white rectangle with black outline
+            image = cv2.rectangle(image, (top_left[0] - 1, top_left[1] - 1), (bottom_right[0] + 1, bottom_right[1] + 1), (0, 0, 0), 1)
+            image = cv2.rectangle(image, top_left, bottom_right, (255, 255, 255), 1)
+
+        # draw pixel value
+        if text_lines:
+            x = line_height
+            y = line_height
+            for line in text_lines:
+                # black text with white outline
+                image = cv2.putText(image, line, color=(0,0,0), org=(x, y), fontFace=font, fontScale=fontScale, thickness=3)
+                image = cv2.putText(image, line, color=(0,255,0), org=(x, y), fontFace=font, fontScale=fontScale, thickness=1)
+                y += line_height
+
+        cv2.imshow(window_name, image)
+
+        k = cv2.waitKey(5) & 0xFF
+        if k == ord('q') or k == ord('Q'):  # 'Q' or 'q'
+            break
+        elif k == 27:  # escape
+            set_hsv_trackbars((0,0,0), (179,255,255))
+            text_lines = []  # clear text
+        elif k == ord('p') or k == ord('P'):  # 'P' or 'p'
+            # print current HSV range
+            print_hsv_trackbars()
+
+    print_hsv_trackbars()
+
+    if cap is not None:
+        cap.release()
+
+    cv2.destroyAllWindows()
+
+if __name__ == "__main__":
+    import argparse
+
+    parser = argparse.ArgumentParser()
+    parser.add_argument("-c", "--camera", type=int, default=0,
+                        help = "index of camera if using multiple cameras")
+    parser.add_argument("-wd", "--width", type=int, default=640,
+                        help = "width of image to capture")
+    parser.add_argument("-ht", "--height", type=int, default=480,
+                        help = "height of image to capture")
+    parser.add_argument("-f", "--file", type=str,
+                        help = "path to image file to user rather that a camera")
+
+    # Read arguments from command line
+    args = parser.parse_args()
+
+    image = None
+    help = []
+    if args.file is not None:
+        image = cv2.imread(args.file)
+        if image is None:
+            help.append("-f/--file did not resolve to an image file.")
+    else:
+        if args.camera < 0:
+            help.append("-c/--camera must be >= 0")
+        if args.width < 160:
+            help.append("-wd/--width must be >= 160")
+        if args.height < 120:
+            help.append("-ht/--height must be >= 120")
+
+    if len(help) > 0:
+        parser.print_help()
+        for h in help:
+            print("  " + h)
+        sys.exit(1)
+
+    print("- click on a pixel to show it's position, RGB and HSV values")
+    print("- select an area to sample low and high HSV value for an image mask OR")
+    print("- adjust the trackbars to choose low and high HSV values for an image mask")
+    print("- press Escape to reset the low and high hsv value")
+    print("- press 'q' to quit")
+
+    main(args.camera, args.width, args.height, image)