How To Convert From Float 32 To 8 Bit Without Losing Information?

I tried to find contours in my image with cv2.findContours. So as it uses CV_8UC1 images I tried to convert my array with dtype=np.uint8, before it was 32 bit. But there I am loosi

Solution 1:

I found a solution myself:

First I used the 32-bit image to find the contours with cv2.threshold in the 32-bit image. After this I convert the 32-bit array to 8-bit np.array(img_threshold_32bit,dtype=np.uint8) without losing any contours. So now the input for cv2.drawContours is an 8-bit array.

But I still have the problem that the bounding-box is not draw in the plot. Any ideas?

Here is the code:

img_hr = np.array(b[1])

hierachy, img_threshold_32bit = cv2.threshold(img_hr, 100, 255, cv2.THRESH_BINARY)
img_8bit = np.array(img_threshold_32bit,dtype=np.uint8)
contours,_ = cv2.findContours(img_8bit, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
cv2.drawContours(img_8bit, contours, -1, (0, 255, 0), 2, cv2.LINE_AA)

forcntin contours:
      rect = cv2.minAreaRect(cnt)
      box = cv2.boxPoints(rect)
      box = np.int0(box)
      cv2.drawContours(img_8bit,[box],0,(0,0,255),2)
      cv2.circle(img_8bit,(int(rect[0][0]),int(rect[0][1])),5,(255,0,0),-1)

plt.imshow(img_8bit)

Solution 2:

because you draw yourself drawContours only draws contours outlines or filled contours. you must be find a rectangle coords for each contour by using boundingRec or minAreaRect then draw it by using drawing functions of opencv

check this sample code https://github.com/birolkuyumcu/opencvbook_python/blob/master/Ders6/Ders6.py#L114