[Python] cropping a gif file by removing the white spaces

I am trying to crop the gif by identifying the objects within the file and eliminating the spaces where there are no objects. I have a code which splits the gif by processing each frame of the gif. But it is somehow generating the static picture. Below is the code.

from PIL import Image

import numpy as np
import cv2 as cv


def process_frame(frame):
frame = np.array(frame)


if len(frame.shape) == 3 and frame.shape[2] == 4: # Check if it's RGBA (with alpha channel)
frame = cv.cvtColor(frame, cv.COLOR_RGBA2RGB)
elif len(frame.shape) == 2: # If the frame is grayscale (1 channel)
frame = cv.cvtColor(frame, cv.COLOR_GRAY2RGB)


gray = cv.cvtColor(frame, cv.COLOR_RGB2GRAY)

th = 240
(th, mask) = cv.threshold(gray, th, 255, cv.THRESH_BINARY_INV)

contours, _ = cv.findContours(mask, cv.RETR_EXTERNAL, cv.CHAIN_APPROX_SIMPLE)

if contours:
x, y, w, h = cv.boundingRect(contours[0])
cropped_frame = frame[y:y + h, x:x + w]
return cropped_frame
else:
return frame

gif_path = 'Animation.gif'
gif = Image.open(gif_path)

processed_frames = []

for frame_idx in range(gif.n_frames):
gif.seek(frame_idx)
frame = gif.copy() # Copy the frame to process it
cropped_frame = process_frame(frame)
processed_frames.append(cropped_frame)

# Now, save the processed frames as a new GIF
output_gif_path = 'output_cropped.gif'

# Convert frames back to PIL format (as gif.save() expects a list of PIL frames)
pil_frames = [Image.fromarray(f) for f in processed_frames]
pil_frames[0].save(output_gif_path, save_all=True, append_images=pil_frames[1:],
loop=0, duration=gif.info['duration'])

print(f"GIF saved to {output_gif_path}")


Thanks for your help!



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