How to use the command 'rpicam-still' (with examples)

The rpicam-still command is a versatile tool used to capture images using a Raspberry Pi camera. It offers several unique features that are missing from its counterpart rpicam-jpeg, particularly catering to those who need specific encoding options or want to utilize extended features like capturing raw or long-exposure images. It’s a go-to solution for camera enthusiasts and developers working on Raspberry Pi projects that involve image capture.

Use case 1: Capture a photo with different encoding

Code:

rpicam-still -e bmp -o path/to/file.bmp

Motivation:

Capturing images in different encoding formats is crucial for various applications. For instance, BMP format is a raw format that is widely used when image compression is not an option due to quality requirements. PNG is beneficial for images that require lossless compression. Using the appropriate encoding can optimize images for the intended application, whether for image processing, graphical representations, or storage purposes.

Explanation:

• -e bmp: This option specifies the encoding format for the captured image. The user can choose from several formats such as BMP, PNG, RGB, and YUV420. Each encoding serves different purposes and may affect the image quality and file size.
• -o path/to/file.bmp: This specifies the output path and the filename for the captured image. The file extension matches the encoding type to ensure compatibility.

Example Output:

Upon running the command, a high-quality BMP image file named file.bmp will be saved in the specified directory, ready for further processing or analysis.

Use case 2: Capture a raw image

Code:

rpicam-still -r -o path/to/file.jpg

Motivation:

Capturing raw images is often necessary in professional photography and imaging applications where post-processing is essential. Raw images retain all the data captured by the sensor, without any alteration or compression, allowing for detailed and high-fidelity editing afterward. Users in fields like astrophotography, biological research, or any domain requiring absolute precision would benefit from capturing raw images.

Explanation:

• -r: This flag indicates that a raw image will be captured. Capturing raw data provides unprocessed image details that are critical when post-processing and exact color grading are needed.
• -o path/to/file.jpg: The output path where the image will be saved. Although the file extension is .jpg, the image data will be raw, meaning it contains more information than a standard JPEG image.

Example Output:

A raw image named file.jpg will be stored at the specified location. The file will carry more details than a typical JPEG, making it perfect for detailed enhancements and analysis.

Use case 3: Capture a 100 second exposure image

Code:

rpicam-still -o path/to/file.jpg --shutter 100000

Motivation:

Long exposure photography captures brilliant paths of light and motion on camera. It is commonly used to create a smooth, dreamy effect over bodies of water, and to capture light trails from moving vehicles or celestial movements. A 100 second exposure allows capturing such imagery with intense detail and unique photographic effects, making it invaluable for artistic and scientific photography pursuits.

Explanation:

• -o path/to/file.jpg: Determines where the output image will be saved and its filename. The file will be in JPEG format.
• --shutter 100000: Sets the shutter speed for the camera in microseconds, equating to a 100 second exposure (100000 microseconds being equal to 100 seconds). Longer shutter speeds allow more light to hit the camera sensor, thus enabling captivating effects suitable for astrophotography, landscape photography, and dynamic night photography.

Example Output:

An image file called file.jpg will be created, showcasing beautifully captured long exposure effects, ideal for creative or detailed examination of dynamic lighting or movements.

Conclusion:

The rpicam-still command provides a robust portfolio of options for capturing various types of images using a Raspberry Pi camera. From selecting specific encoding formats to capturing detailed raw images and implementing long exposure techniques, it empowers users to tailor their photography to precise requirements. Each of its functionalities can significantly aid in producing high-quality images for both professional and hobbyist use. By understanding and leveraging these options, users can expand the capabilities of their Raspberry Pi projects and enhance their photographic endeavors.