Apparatus and method for dynamic range transforming of images

An encoding apparatus comprising:

• a receiver circuit, wherein the receiver circuit is arranged to receive an encoded image;
• a generator circuit,
• wherein the generator circuit is arranged to generate an image signal,
• wherein the image signal comprises an encoded image, a dynamic range transform control data and a target display reference,
• wherein the target display reference specifies a dynamic range of a target display,
• wherein the target display is a display for which the encoded image is optimized;
• wherein the target display reference comprises a white point luminance of the target display,
• wherein the dynamic range transform control data comprises different dynamic range transform parameters for different maximum luminance levels of the target display;
• and
• a transmitter circuit, wherein the transmitter circuit is arranged to transmit the image signal.

An image processing method comprising:

• receiving an image signal,
• wherein the image signal comprises at least an encoded image, a dynamic range transform control data and a target display reference,
• wherein the target display reference specifies a dynamic range of a target display,
• wherein the target display is a display for which the encoded image is optimized,
• wherein the target display reference comprises a white point luminance of the target display;
• wherein the dynamic range transform control data comprises different dynamic range transform parameters for different maximum luminance levels of the target display;
• generating an output image by applying a dynamic range transform to the encoded image, dynamic range transform is bases on the white point luminance, a reference white point luminance, and the dynamic range transform control data;
• and
• outputting an output image signal, wherein the output image signal comprises the output image.

A method of transmitting an image signal, the method comprising:

• receiving an encoded image;
• generating an image signal,
• wherein the image signal comprises the encoded image, a dynamic range transform control data and a target display reference,
• wherein the target display reference specifies a dynamic range of a target display,
• wherein the target display is a display for which the encoded image is optimized,
• wherein the target display reference comprises a white point luminance of the target display,
• wherein the different dynamic range transform parameters for different maximum luminance levels of the target display;
• and
• transmitting the image signal.