In this task, you will implement a function calculate_brightness(img) that calculates the average brightness of a grayscale image. The image is represented as a 2D matrix, where each element represents a pixel value between 0 (black) and 255 (white).
Your Task: Implement the function calculate_brightness(img) to return the average brightness rounded to two decimal places. If the image matrix is empty, has inconsistent row lengths, or contains invalid pixel values (outside the range 0-255), the function should return -1.
Example:
img = [
[100, 200],
[50, 150]
]
print(calculate_brightness(img))
Output: 125.0
Consider a grayscale image represented as a 2D matrix where each element represents a pixel value between 0 (black) and 255 (white):
\[ Image = \begin{pmatrix} p_{11} & p_{12} \\ p_{21} & p_{22} \end{pmatrix} \]The average brightness is calculated as:
\[ Brightness = \frac{\sum_{i=1}^{m} \sum_{j=1}^{n} p_{ij}}{m \times n} \]where:
Things to note:
def calculate_brightness(img):
# Check if image is empty or has no columns
if not img or not img[0]:
return -1
rows, cols = len(img), len(img[0])
# Check if all rows have same length and values are valid
for row in img:
if len(row) != cols:
return -1
for pixel in row:
if not 0 <= pixel <= 255:
return -1
# Calculate average brightness
total = sum(sum(row) for row in img)
return round(total / (rows * cols), 2)
There’s no video solution available yet 😔, but you can be the first to submit one at: GitHub link.