Creating an HDR image, internal signal processing and integration

Today video contents market requires to deal with both low and high dynamic range data. Even more challenging is the fact that the high dynamic range contents comes from many different origin and specifications.

SIM2 engineer managed to take in to account the unavoidable complexity providing the users with unrivalled flexibility with very little tradeoff in terms of ease of use.

Expansion of standard dynamic source to high dynamic range image: inverse tone mapping processing

Most of us have experience of Tone mapping, a well known technique used in image processing to simulate the appearance of High Dynamic Range images when reproduced in media with a more limited dynamic range. Print-outs, CRT or LCD monitors, and projectors all have a limited dynamic range which is inadequate to reproduce the full range of light intensities present in natural scenes. Essentially, tone mapping addresses the problem of strong contrast reduction from the scene values (radiance) to the displayable range while preserving the image details and color appearance important to appreciate the original scene content. TMOs compress the luminance range while trying to maintain contrast.
Sim2 HDR47 series display allows for the first time to display HDR images without the need to apply any Tone Mapping.

The inverse function of tone mapping is called (no surprise) inverse tone mapping. 
It expands a Low Dynamic Range content into an HDR content. 
Given that the majority of today's media is stored in low dynamic range even when its origin featured a wider range, Inverse Tone Mapping Operators could thus potentially “revive” all of this content. 
SIM2 HDR47E series display, used in Normal mode, leverages the powerful internal FPGA board to apply an inverse tone mapping operator to the input contents on the fly. The result is a better and more realistic image on the screen.

Integration of backlight and LCD panel for the creation of the final image

The final image is the result of the integration of two components: back lightning and panel.

Defining the precise behaviour of the two streams requires custom refined algorithms.

A simplified functional block diagram helps understanding the main modules, interactions and data streams leading to the final result.

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The system as a whole takes into account different entry points according to the kind of source data. True HDR data skip the first processing modules devoted to inverse tome mapping operations.

LEDs segment calculator module and Back light unit field simulator processing module take into account several input feeds in order to compute which should be the final hardware activation. The processing process takes into account some additional side-loaded parameters, the most important are a gain control and the application of calibration modifiers, which are specific to the monitor and to the user implementation.


A simpler block diagram focus on functional description of monitor data flow.

image processing hdr

The monitor data internal representation always features 30 bit depth per colour, which is later processed into 8 bit per color to the LCD panel and 12 bit LEDs activation level.