Common Image File Formats and How to Read/Write Them with OpenCV

BMP - Windows Bitmap is often used in operating systems because it stores uncompressed image data, making it suitable for high‑quality applications like desktop wallpapers or icon design.

import cv2
# Read BMP file
img = cv2.imread('example.bmp')
# Display image
cv2.imshow('BMP Image', img)
cv2.waitKey(0)
cv2.destroyAllWindows()
# Save image as BMP
cv2.imwrite('output.bmp', img)

PNG - Portable Network Graphics supports an alpha channel, making it ideal for web design, logos, and any graphics that require transparent backgrounds.

# Read PNG file (including alpha channel)
img = cv2.imread('example.png', cv2.IMREAD_UNCHANGED)
# Display image (OpenCV windows do not show transparency)
cv2.imshow('PNG Image', img[:, :, :3])  # show without alpha
cv2.waitKey(0)
cv2.destroyAllWindows()
# Save image as PNG
cv2.imwrite('output.png', img)

JPEG/JPG - Joint Photographic Experts Group is a widely used lossy compression format suitable for photographs and web images due to its high compression ratio and acceptable quality loss.

# Read JPEG file
img = cv2.imread('example.jpg')
# Display image
cv2.imshow('JPEG Image', img)
cv2.waitKey(0)
cv2.destroyAllWindows()
# Save image as JPEG with quality parameter
cv2.imwrite('output.jpg', img, [int(cv2.IMWRITE_JPEG_QUALITY), 90])

JPE - Alternative JPEG Extension is simply another file extension for the same JPEG format; handling is identical.

# Read JPE file
img = cv2.imread('example.jpe')
# Save image as JPE
cv2.imwrite('output.jpe', img)

TIF/TIFF - Tagged Image File Format is commonly used in publishing and high‑end image editing because it can store multiple layers and supports lossless compression.

# Read TIFF file
img = cv2.imread('example.tiff')
# Save image as TIFF
cv2.imwrite('output.tiff', img)

WEBP - WebP Image Format offers better compression efficiency for both lossy and lossless use cases, making it suitable for reducing website image load times.

# Read WEBP file
img = cv2.imread('example.webp')
# Save image as WEBP
cv2.imwrite('output.webp', img)

SR - Sun Raster is an older format mainly used on Sun Microsystems operating systems and is rarely used today.

# Read SR file
img = cv2.imread('example.sun')
# Save image as SR
cv2.imwrite('output.sun', img)

PBM, PGM, PPM - Portable Bitmap/Graymap/Pixmap are simple ASCII or binary formats for black‑and‑white, grayscale, and color images respectively, often used in teaching and testing image‑processing algorithms.

# Read PPM file (similar for PBM/PGM)
img = cv2.imread('example.ppm')
# Save image as PPM
cv2.imwrite('output.ppm', img)

PFM - Portable FloatMap stores floating‑point pixel values, useful for scientific visualisation and certain image‑processing tasks; OpenCV does not natively support PFM.

EXR - OpenEXR High Dynamic Range is designed for visual effects, supporting multiple channels and high‑precision data; OpenCV may require a build with EXR support.

# Read EXR file (ensure OpenCV built with EXR support)
img = cv2.imread('example.exr', cv2.IMREAD_ANYDEPTH | cv2.IMREAD_COLOR)
# Save image as EXR
cv2.imwrite('output.exr', img)

JPEG 2000 family (JP2, JPC, J2K, J2C, PGX, PXM, PNM) provides advanced compression for archival and medical imaging, preserving quality at higher compression ratios.

# Read JPEG 2000 file (support depends on OpenCV build)
img = cv2.imread('example.jp2')
# Save image as JP2
cv2.imwrite('output.jp2', img)