# I420toRGB¶

Versioned name : I420toRGB-8

Category : Image processing

Short description : I420toRGB performs image conversion from I420 to RGB format.

Detailed description:

Conversion of each pixel from I420 (YUV) to RGB space is represented by the following formulas (same as in NV12toRGB):

\begin{split}\begin{aligned} & R = 1.164 \cdot (Y - 16) + 1.596 \cdot (V - 128) \\ & G = 1.164 \cdot (Y - 16) - 0.813 \cdot (V - 128) - 0.391 \cdot (U - 128) \\ & B = 1.164 \cdot (Y - 16) + 2.018 \cdot (U - 128) \end{aligned}\end{split}

Then R, G, B values are clipped to range (0, 255).

Inputs:

Input I420 image tensor shall have NHWC (also known as NYXC) layout and can be represented in two ways:

• Single plane :

• 1 : Tensor of type T. Required. Dimensions:

• N - batch dimension

• H - height dimension is 1.5x bigger than the image height

• W - width dimension is the same as the image width

• C - channels dimension is equal to 1 (one plane)

• Three separate planes - Y, U and V :

• 1 : Tensor of type T representing Y plane. Required. Dimensions:

• N - batch dimension

• H - height dimension is the same as the image height

• W - width dimension is the same as the image width

• C - channels dimension is equal to 1 (only Y channel)

• 2 : Tensor of type T representing U plane. Required. Dimensions:

• N - batch dimension. Shall be the same as the batch dimension for Y plane

• H - height dimension shall be half of the image height (for example, image_height / 2)

• W - width dimension shall be half of the image width (for example, image_width / 2)

• C - channels dimension shall be equal to 1 (U channel)

• 3 : Tensor of type T representing V plane. Required. Dimensions:

• N - batch dimension. Shall be the same as the batch dimension for Y plane

• H - height dimension shall be half of the image height (for example, image_height / 2)

• W - width dimension shall be half of the image width (for example, image_width / 2)

• C - channels dimension shall be equal to 1 (V channel)

Outputs:

• 1 : A tensor of type T representing an image converted in RGB format. Dimensions:

• N - batch dimension

• H - height dimension is the same as the image height

• W - width dimension is the same as the image width

• C - channels dimension is equal to 3. The first channel is Red, the second one is Green, the last one is Blue

Types:

• T : uint8 or any supported floating-point type.

Examples:

Example 1

<layer ... type="I420toRGB">
<input>
<port id="0">
<dim>1</dim>
<dim>720</dim>
<dim>640</dim>
<dim>1</dim>
</port>
</input>
<output>
<port id="1">
<dim>1</dim>
<dim>480</dim>
<dim>640</dim>
<dim>3</dim>
</port>
</output>
</layer>

Example 2

<layer ... type="I420toRGB">
<input>
<port id="0">  <!-- Y plane -->
<dim>1</dim>
<dim>480</dim>
<dim>640</dim>
<dim>1</dim>
</port>
<port id="1">  <!-- U plane -->
<dim>1</dim>
<dim>240</dim>
<dim>320</dim>
<dim>1</dim>
</port>
<port id="2">  <!-- V plane -->
<dim>1</dim>
<dim>240</dim>
<dim>320</dim>
<dim>1</dim>
</port>
</input>
<output>
<port id="1">
<dim>1</dim>
<dim>480</dim>
<dim>640</dim>
<dim>3</dim>
</port>
</output>
</layer>