tv — tv shield driver

The tv module is used for controlling the tv shield.

Example usage:

import sensor, tv

# Setup camera.
sensor.reset()
sensor.set_pixformat(sensor.RGB565)
sensor.set_framesize(sensor.SIF)
sensor.skip_frames()
tv.init()

# Show image.
while(True):
    tv.display(sensor.snapshot())

Functions

tv.init([type=tv.TV_SHIELD[, triple_buffer=False]])

Initializes an attached tv output module.

type indicates how the lcd module should be initialized:

triple_buffer If True then makes updates to the screen non-blocking in tv.TV_SHIELD mode at the cost of 3X the display RAM (495 KB).

tv.deinit()

Deinitializes the tv module, internal/external hardware, and I/O pins.

tv.width()

Returns 352 pixels. This is the sensor.SIF resolution.

tv.height()

Returns 240 pixels. This is the sensor.SIF resolution.

tv.type()

Returns the type of the screen that was set during tv.init().

tv.triple_buffer()

Returns if triple buffering is enabled that was set during tv.init().

tv.refresh()

Returns 60 Hz.

tv.channel([channel])

For the wireless TV shield this sets the broadcast channel between 1-8. If passed without a channel argument then this method returns the previously set channel (1-8). Default is channel 8.

tv.display(image[, x=0[, y=0[, x_scale=1.0[, y_scale=1.0[, roi=None[, rgb_channel=-1[, alpha=256[, color_palette=None[, alpha_palette=None[, hint=0[, x_size=None[, y_size=None]]]]]]]]]]]])

Displays an image whose top-left corner starts at location x, y. You may either pass x, y separately, as a tuple (x, y), or neither.

x_scale controls how much the displayed image is scaled by in the x direction (float). If this value is negative the image will be flipped horizontally.

y_scale controls how much the displayed image is scaled by in the y direction (float). If this value is negative the image will be flipped vertically.

roi is the region-of-interest rectangle tuple (x, y, w, h) of the image to display. This allows you to extract just the pixels in the ROI to scale.

rgb_channel is the RGB channel (0=R, G=1, B=2) to extract from an RGB565 image (if passed) and to render on the display. For example, if you pass rgb_channel=1 this will extract the green channel of the RGB565 image and display that in grayscale.

alpha controls how opaque the image is. A value of 256 displays an opaque image while a value lower than 256 produces a black transparent image. 0 results in a perfectly black image.

color_palette if not -1 can be sensor.PALETTE_RAINBOW, sensor.PALETTE_IRONBOW, or a 256 pixel in total RGB565 image to use as a color lookup table on the grayscale value of whatever the input image is. This is applied after rgb_channel extraction if used.

alpha_palette if not -1 can be a 256 pixel in total GRAYSCALE image to use as a alpha palette which modulates the alpha value of the input image being displayed at a pixel pixel level allowing you to precisely control the alpha value of pixels based on their grayscale value. A pixel value of 255 in the alpha lookup table is opaque which anything less than 255 becomes more transparent until 0. This is applied after rgb_channel extraction if used.

hint can be a logical OR of the flags:

x_size may be passed if x_scale is not passed to specify the size of the image to display and x_scale will automatically be determined passed on the input image size. If neither y_scale or y_size are specified then y_scale internally will be set to be equal to x_size to maintain the aspect-ratio.

y_size may be passed if y_scale is not passed to specify the size of the image to display and y_scale will automatically be determined passed on the input image size. If neither x_scale or x_size are specified then x_scale internally will be set to be equal to y_size to maintain the aspect-ratio.

Constants

tv.TV_NONE

Returned by tv.type() when the this module is not initialized.

tv.TV_SHIELD

Used to initialize the TV module.