class ImageIO – ImageIO object

The ImageIO class allows you to read/write OpenMV Image objects in their native form to disk or to memory, providing fast random-access read/write of frames.

class image.ImageIO(path: str | Tuple[int, int, int], mode: str | int)

Creates an ImageIO object.

If path is a string, it is treated as a file path on disk. mode must be 'r' to open for reading or 'w' to open for writing.

If path is a 3-value tuple (w, h, pixformat), it is treated as in-memory storage. mode is then the integer number of image buffers (frames) to pre-allocate. The in-memory storage buffer is not allowed to grow after allocation. pixformat is a pixformat constant such as image.GRAYSCALE, image.RGB565, image.BAYER, or image.JPEG.

type() → int

Returns whether the ImageIO object is a FILE_STREAM or MEMORY_STREAM.

is_closed() → bool

Returns True if the ImageIO object is closed and can no longer be used.

count() → int

Returns the number of frames stored.

offset() → int

Returns the current image index offset.

version() → int | None

Returns the stream version if the object is a FILE_STREAM. Returns None for MEMORY_STREAM objects.

buffer_size() → int | None

Returns the per-frame buffer size in bytes for MEMORY_STREAM objects. Returns None for FILE_STREAM objects.

For memory streams, buffer_size() * count() == size().

size() → int

Returns the total number of bytes used on disk or in memory.

write(img: Image) → ImageIO

Writes img to the stream. For file streams, the file grows as new images are appended. For memory streams, the image is written to the current pre-allocated slot before the offset advances.

Returns the ImageIO object.

read(copy_to_fb: bool = True, *, loop: bool = True, pause: bool = True) → Image | None

Returns the next image from the stream and advances the offset.

copy_to_fb if True, the image is loaded into the frame buffer (like sensor.snapshot()). If False, the image is allocated on the MicroPython heap.

loop if True, automatically seeks to the beginning of the stream when the end is reached. If False, returns None at end-of-stream (file streams only).

pause if True, pauses for the originally recorded inter-frame interval to match the source frame rate.

seek(offset: int) → ImageIO

Seeks to the image slot number offset. Works for both file and memory streams.

Returns the ImageIO object.

sync() → ImageIO

Flushes pending data to disk for file streams. No-op for memory streams.

Returns the ImageIO object.

close() → None

Closes the ImageIO object. For memory streams, frees the allocated buffer. For file streams, closes the file and writes out all metadata.

FILE_STREAM: int

The ImageIO object was opened on a file.

MEMORY_STREAM: int

The ImageIO object was opened in memory.