Matplotlib - Image Display
How can you correctly swap the red and blue channels of an RGB image array
img using numpy without losing data?How can you correctly swap the red and blue channels of an RGB image array img using numpy without losing data?
hard📝 Application Q9 of 15
Step-by-Step Solution
Solution:
Step 1: Understand the problem
Swapping red (channel 0) and blue (channel 2) requires temporarily storing one channel to avoid overwriting.Step 2: Analyze options
temp = img[:, :, 0] img[:, :, 0] = img[:, :, 2] img[:, :, 2] = temp uses a temporary variable to hold red channel before assignment, ensuring no data loss.Step 3: Why others are incorrect
img[:, :, [0, 2]] = img[:, :, [2, 0]] tries to assign slices simultaneously but numpy does not support this direct swapping. img[:, :, 0], img[:, :, 2] = img[:, :, 2], img[:, :, 0] attempts tuple unpacking which does not work for numpy arrays. img[:, :, 0] = img[:, :, 2] img[:, :, 2] = img[:, :, 0] overwrites red channel first, losing original data.Final Answer:
Use a temporary variable to swap channels safely -> Option AQuick Check:
Use temp variable to avoid overwriting [OK]
Quick Trick: Use temp variable to swap channels safely [OK]
Common Mistakes:
- Overwriting one channel before saving it
- Assuming tuple unpacking works on numpy slices
- Trying to swap channels without temporary storage
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