WO2008072162A2

WO2008072162A2 - Video processing device and method of color gamut mapping

Info

Publication number: WO2008072162A2
Application number: PCT/IB2007/054988
Authority: WO
Inventors: Petrus M. De Greef
Original assignee: Nxp B.V.
Priority date: 2006-12-11
Filing date: 2007-12-10
Publication date: 2008-06-19
Also published as: WO2008072162A3

Abstract

A video processing device is provided which comprises a color gamut mapping matrix unit (CGMM, ACGMM) for providing a color gamut mapping correction of an input signal and a mixing unit (MU) for applying a mix of color gamut mapped signals and the input signal based on a first correction factor (α) by mixing properties of the color gamut mapped input pixels with properties of the input pixels corrected by the first correction factor. The video processing device furthermore comprises a clipping unit (CLU) for clipping properties of pixels of an output of the mixing unit if these properties are not within a predefined range. Furthermore, a first control unit (CTRL1) is provided for determining the first correction factor (α) based on the amount of over and/or underflowing of pixels outputted from the mixing unit (MU). Hence, a correction of the input pixels is performed according to the overall underflowing of pixels.

Description

VIDEO PROCESSING DEVICE AND METHOD OF COLOR GAMUT MAPPING

FIELD OF THE INVENTION

The present invention relates to a video processing device for processing color image data and a method of color gamut mapping.

BACKGROUND OF THE INVENTION

More and more mobile electronic devices are designed with a color display device for displaying color images. These color images can for example be generated by a camera or a video processor. The supplied color image data may have to undergo an image processing to improve the appearance of the image on the display device. Nowadays, multi- media data have to be displayed on a mobile phone, on a multi-media portable player, etc. Typically, the display technology used in these mobile devices has some limitations, in particular with respect to the picture quality and the color reproduction. The colors of the supplied image data are typically encoded according to already existing standards. These standards have been selected to facilitate a design of displays based on the available materials. Accordingly, as long as a camera or a display match the chosen standard, a reasonable reproduction of the colors or image data may be expected.

On the other hand, LCD displays in particular for mobile applications may not be able to meet the requirements of these standards. One of these standards is the sRGB standard, which defines the x-y coordinates of the red, green and blue light source in connection with a reference white point. The primary RGB coordinates of the sRGBstandard define a triangle drawn in the Y-xy diagram. The Y component represents the luminance of a pixel (perpendicular to the x-y axis) while the x-y coordinate relates to a unique color with respect to saturation and hue. Preferably, the color coordinates of each encoded pixel lie inside or on the border of this triangle. For many mobile LCD displays, their color gamut (display triangle) is smaller than the sRGB reference such that several artifacts may be the result. These artifacts may include a lack of saturation due to a smaller gamut of the display of the mobile device. A further artifact may relate to hue errors as the individual color primaries can be different with respect to the sRGB primaries. Furthermore, the reference white point may be shifted such that black and white parts in a scene may be represented in a color. To cope with these problems, color gamut mapping is used to process input pixels such that the colors on a display with a smaller gamut are reproduced equal to a reference display.

WO 2005/109854 discloses a method for processing color image data to be displayed on a target device. Input pixel data within a source color gamut is received. The input pixel data in said source color gamut is mapped to a target color gamut which can be associated to a target device. The mapping is controlled according to a color saturation value of the input pixel data.

Fig. 1 shows a block diagram of a basic color gamut mapping. The input image data are processed by a gamma function 10. The output of the gamma function 10 undergoes a color gamut mapping function 20 by processing the input pixel data with a static matrix. After the color gamut mapping function 20, the output thereof is processed by a hard clipper function 30. Here, negative values of R, G, B are clipped to zero and a value of the RGB is set or clipped to 255 for 24-bit RGB pixel data if the value of the RGB is larger than 255. The output of the hard clipper function 30 is processed by the de-gamma function 40 and the output of the de-gamma function 40 is supplied to a display in a target device. The gamma function 10 is required as the input image data or pixels relate to the video domain. The values of the RGB signal are now proportional to the luminance of the three primary light sources. By performing a gamut mapping, light sources are lineary mixed to achieve a desired color. Gamut mapping is preferably performed in the light domain. The gamma transformation performed in the gamma function 10 corresponds to a non- linear operation and will increase the required resolution of the RGB signal in the digital domain. The coefficients of the gamut mapping matrix in the gamut mapping function 20 are chosen such that an input RGB luminance value can be directly mapped into a new RGB luminance value for the display of the mobile application. In other words, the matrix is designed to adapt the ratio between the RGB subpixels. The coefficients of the gamut mapping matrix can be calculated:

MTX_cgm = (MTX_d1Sp)^{"1 •} MTX_8RGB wherein the MTX_SRGB and the MTXd_lsp matrices are used to translate a RGB value to the XYZ domain and back. These matrices are determined based on the primary colors and a reference white point of the input standard and display module.

However, increasing the color saturation of an image or video signal is a well- known technique since the appearance of the first color displays. In modern TV systems, this can be implemented by a manual control such that the quality of the images is increased as long as no clipping artifacts occur. Known techniques convert one color space to another, perform image processing with respect to the luminescence or the color and convert the resulted image back into the initial color space. Such a technique may be used to amplify the saturation of RGB signals in the YUV or Yxy domain such that colors can be modified without affecting the luminescence. Moreover, smart clipping is used to deal with signals which are out of range.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a video processing device and a method of color gamut mapping with an improved color gamut mapping.

This object is solved by a video processing unit according to claim 1 and by a method according to claim 6.

Therefore, a video processing device is provided which comprises a color gamut mapping matrix unit for providing a color gamut mapping correction of an input signal and a mixing unit for applying a mix of color gamut mapped signals and the input signal based on a first correction factor by mixing properties of the color gamut mapped input pixels with properties of the input pixels corrected by the first correction factor. The video processing device furthermore comprises a clipping unit for clipping properties of pixels of an output of the mixing unit if these properties are not within a predefined range. Furthermore, a first control unit is provided for determining the first correction factor based on the amount of over and/or underflowing of pixels outputted from the mixing unit. Hence, a correction of the input pixels is performed according to the over- or underflowing of pixels.

According to an aspect of the invention, a luminescence saturation and hue detection and regulation unit provides a new set of matrix coefficients towards the color gamut mapping matrix unit for each pixel depending on the luminescence, the saturation and the hue properties of the pixel. The color gamut mapping matrix unit is adapted to provide an adaptive color gamut mapping correction.

According to still a further aspect of the invention, a spatial filter unit provides data towards the first control unit according to the spatial correlation properties of the input frame of input data. The first control unit is adapted to determine a first correction factor based on the amount of over or underflowing of pixels outputted from the mixing unit as well as based on spatial correlation properties of the input frame. The color gamut mapping matrix unit is adapted to provide a static color gamut mapping correction. According to still a further aspect of the invention, an amplifying unit is provided for amplifying properties of the output pixels. A second control unit is provided for determining a second correction factor based on the amount of over or underflowing of pixels. The amplifying unit is adapted to amplify properties of the output pixels according to the second correction factor.

According to still a further aspect of the invention, an offset unit is provided for adding an offset to properties of the output pixels. A third control unit is provided for determining a third correction factor based on the amount of over or underflowing of pixels. The offset unit is adapted to add an offset to properties of the output pixels according to the third correction factor.

The invention also relates to a method of color gamut mapping in a video processing device. A color gamut mapping correction of an input signal is provided by means of a color gamut mapping matrix. A mix of color gamut mapped signals and the input signals is applied based on a first correction factor (α) by mixing properties of the color gamut mapped input pixels with properties of the input pixels corrected by the first correction factor (α).

The invention relates to the recognition that the above described color gamut mapping may lead to subpixels which are out of range (negative or positive out of range). To avoid such values, a clipping operation (hard, soft or smart) is performed. An inverse gamma function may be used to transform the pixels back to the video domain as a display typically cannot handle the luminance values directly, e.g. because the display comprises a standard interface hardware.

In order to obtain an optimal color reproduction of the original sRGB images on a display with a limited color gamut an adaptive color gamut mapping technique can be performed, wherein the saturation, the hue and the white-point is corrected and the luminescence is maintained. The use of color gamut mapping techniques may however introduce significant clipping artifacts thus reducing the quality. If no clipping occurs, images can be corrected by means of the color gamut mapping. The correction is only partly applied in order to reduce clipping artifacts. The estimated image quality reduction corresponds to correction factor α. The value of the factor α is dependent on potential clipping artifacts of the pixels of an image. The value of α (range between 0 and 1) is determined for each image and is used to control the color gamut mapping correction. If the correction factor α corresponds to zero no correction and no clipping will occur, while if the correction factor α corresponds to 1 a full correction and a potential clipping will occur.

V₀Ut = [M_CGM]*V_in*(α)+V_m*(l-α)

The invention also relates to the idea to provide a color gamut mapping method where a clipping out of range values is avoided.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages and embodiments of the invention will now be described in more detail with respect to the drawings. Fig. 1 shows a block diagram of a color gamut mapping system according to the prior art,

Fig. 2 shows a block diagram of a display system according to the invention, Fig. 3 shows a block diagram of a color gamut mapping system according to a first embodiment, Fig. 4 shows a graph depicting the relation between counter values and a reduction of the image quality,

Fig. 5 shows a block diagram of a color gamut mapping system according to a second embodiment,

Fig. 6 shows a block diagram of a color gamut mapping system according to a third embodiment,

Fig. 7 shows a block diagram of a contrast enhancement means according to a fourth embodiment,

Fig. 8 shows a block diagram of a combination of a color gamut mapping system and a contrast enhancement system according to a fifth embodiment, and Fig. 9 shows a block diagram of a combination of a color gamut mapping system and a contrast enhancement means according to a sixth embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Fig. 2 shows a block diagram of a basic architecture of a display system according to the invention. The display system comprises a display driver DD and a display panel. The display driver DD comprises a frame memory FM and an adaptive color gamut mapping unit ACGM. Fig. 3 shows a block diagram of a color gamut mapping unit according to a first embodiment. The color gamut mapping unit ACGM according to a first embodiment can be used in the display system of Fig. 2.

The color gamut mapping unit comprises a static color gamut mapping matrix unit CGMM, a mixing unit, a clipping unit CLU, a count unit CU, a first control unit CTRL and a threshold unit TU. The output of the first control unit CTRLl corresponds to the correction value α. If the video signal is fully color gamut mapping corrected, i.e. the correction factor α corresponds to 1. If a processed frame comprises many pixels, which are over- or under- flowing, the correction factor α is increased such that the correction of the color gamut mapping is reduced. Furthermore, the clipping in the next frame will also be reduced. On the other hand, if the frame to be processed only comprises a few over- or under- flowing pixels, the correction value α is decreased. According to the color gamut mapping unit according to the first embodiment, a feedback loop is introduced by incorporating the count unit CU and the first control unit CTRLl. The output of the first control unit CTRLl corresponds to the correction factor α and is inputted to the mix unit MU. The count unit CU serves to count the under- and over- flowing pixels. The end of each frame (image) is signaled by the End-Of-Frame signal (EOF). This is used by the control unit CTRLl to determine a new value for the correction factor α and to clear the count unit CU.

If oscillations in the color gamut mapping unit are to be avoided, temporal filtering needs to be implemented in the feedback loop. In order to get an optimal setting for still images, the still images need to pass several times.

As an example, the filter for the count unit CU may be implemented as HR filter (Yn = l/2X_n_i + l/4X_n_₂+l/8X_n_₃+... In addition, a hysteresis of approx. 10% can be applied. The partial color gamut mapping correction factor α is modeled by means of an overflow and underflow threshold as stored in the threshold unit TU.

Fig. 4 shows a graph of the influence of the counter values on the correction factor α. Here, the threshold values (Thol : threshold-overflow low; Tho2: threshold-overflow high; Thul : threshold-underflow low; Thu2: threshold-underflow high) will depend on the actually measured display properties. A pixel-based adaptive color gamut mapping method is designed to find an optimal mapping based on pixel properties and to avoid the necessity of significant hard clipping. A color gamut mapping may not be optimal even if each individual pixel can be mapped. Full correction (α = 0) is only possible if no critical colors are in the neighborhood. If it is required to maintain sufficient color modulation with respect to these critical colors, they also require some reduced correction as compared to colors which are not critical.

The color gamut mapping method may also be frame-based and may have some notion of the overall appearances of colors in an image. If no critical colors are present in the image, the reservation of a dynamic range is not required. Here, the almost critical colors may be mapped with a full correction by means of the full dynamic range such that a more correct color reproduction is possible. In these cases, the correction factor α may stay low in order to increase the color gamut mapping correction.

Furthermore, a history analysis or a feedback loop can provide statistical input with respect to a controller but without a notion of spatial or temporal correlation. These spatial or temporal correlation may also add extra dimensions with respect to the color gamut mapping algorithm. It should be noted that slightly modulated parts of an image may be sensitive to small errors and quantisation artifacts while highly modulated parts of the image may require less accuracy. Fig. 5 shows a block diagram of an adaptive color gamut mapping unit according to a second embodiment. This color gamut mapping unit CGM can be used in the display system according to Fig. 2. The color gamut mapping unit CGM comprises a mix unit MU, a clipping unit CU, a count unit CU, a first control unit CTRLl, a threshold unit TU, an adaptive color gamut mapping matrix unit ACGMM and a LSH detection and modulation unit LSH. The LSH detection and modulation LSH is used to provide the matrix coefficients for the color gamut mapping. According to the second embodiment, the input image data are processed by means of a pixel-based automatic color gamut mapping method. The mapping unit will fully correct all unsaturated pixels with limited luminescence and will party correct the remaining pixels based on the pixel properties luminescence, saturation and hue. Advantageously, the pixel-based corrected image data will comprise values at the output of the matrix unit ACGM, which are less out of range and the out of range values are smaller. The mix unit MU may be embodied as a frame-based adaptive mixer in order to reduce the correction of those output values of the matrix unit ACGMM which are out of range. On the other hand, the reduction of the correction will also apply to the fully corrected values of other pixels. Therefore, the frame-based reduction of the correction will only then be employed if many out of range values are present. The count unit CU is used to count out of range values and to determine the correction factor α in the first control unit CTRLl, which is then forwarded each frame to the mix unit MU and applied to the next frame. In this system the reduction of the gamut correction can be prioritized with respect to: hue, saturation and white-point correction.

Fig. 6 shows a block diagram of a color gamut mapping unit according to a third embodiment. The color gamut mapping unit according to the third embodiment substantially corresponds to the color gamut mapping unit according to the second embodiment. However, the color gamut mapping unit according to the third embodiment comprises a static color gamut mapping matrix unit CGMM instead of the adaptive color gamut mapping matrix unit ACGMM according to the second embodiment. Furthermore, the color gamut mapping unit according to the third embodiment comprises a spatial filter unit ST instead of a LSH detection and modulation unit.

The spatial filter ST can be used to detect spatial correlations. If critical colors which are spatially correlated occur with a limited modulation on saturation, hue and luminescence the correction factor can be decreased in order to reduce the color gamut mapping correction and to whereby reduce the artifacts related thereto. Accordingly, the spatial filter ST can be implemented as a one-dimensional low pass filter for filtering the sub- pixels. Such a filtering may provide an effective detection of spatial correlations. Here, the input data are inputted to the spatial filter ST in order to detect any spatial correlatied critical colors. The output of the spatial filter ST is forwarded to the first control unit CTRLl such that a detection of a spatial correlation of critical colors will influence the value of the correction factor α which may be used for a frame-based correction.

Fig. 7 shows a block diagram of a color enhancement means according to a fourth embodiment. The enhancement means or the mapping means comprises an amplifying unit AU, a clipping unit CLU, a threshold unit TU, a count unit CU and a second control unit CTRL2. The amplifying unit AU receives the input video data. If the frame processed by the amplifying unit AU merely comprises a few pixels which are overflowing, the gain factor β is increased. Increasing the gain factor β will also increase the contrast and potential clipping within an up following frame. However, the gain factor β is decreased if many overflowing pixels are present in a frame. Accordingly, the contrast can be adaptively boosted. A temporal filtering may be provided in the feedback loop in order to avoid the above- mentioned oscillations. If still images are processed, they may have to pass the processing several times in order to obtain an optimal setting.

Fig. 8 shows a block diagram of a color gamut mapping unit according to a fifth embodiment. Here, the color mapping unit according to the third and contrast booster unit according to the fourth embodiment are combined into one system. Therefore, the color gamut mapping unit comprises a mixing unit MU, an amplifying unit AU, a clipping unit CLU, a counting unit CU, a threshold unit TU, a color gamut mapping matrix unit CGMM, a spatial filter SF and a first and second control unit CTRLl, CTRL2, which output a correction factor α and a gain factor β, respectively. The estimated reduction of the image quality which may be because of the necessity of clipping is represented by the correction factor α and the gain factor β. The values thereof will depend on potential clipping artifacts in the pixels of an image. Accordingly, for each image, the values α, β must be determined and can be applied to control the amount of adaptive contrast boosting according to the fourth embodiment and the color gamut mapping according to the third embodiment. The output signal correspond to :

V₀Ut = (1+β) * {[McGM]*V_m*(α)+V_m*(l-α)} = [M_CGM]*V_m*(l+β) * (α) + V_1n * (1+ β) * (1-α) = {[M_CGM]*V_m*(α/(l-α)) + V_1n)* (1+ β) * (1- α)

It should be noted that the values (1+ β), α, (1-α), (α/(l-α)) are only calculated once for each frame.

For the case that no clipping occurs, the images are completely corrected with color gamut mapping and some extra luminescence or contrast may be added. However, if significant overflow clipping occurs, first of all, the gain factor β is reduced. If the clipping remains, the correction factor α is reduced. The advantage of the color gamut mapping unit according to the fifth embodiment is that adaptive color gamut mapping with a feedback and adaptive contrast boosting with a feedback are integrated into one unit such that power as well as costs can be saved.

According to the fifth embodiment, the input video data is fully color gamut mapping corrected and is not amplified. If a processed frame has only several pixels which are overflowing, the gain factor β is increased such that the contrast and potential clipping in the next frame is increased. However, if the processed frame comprises several pixels which are overflowing, the gain factor β is decreased. Furthermore, if the processed frame comprises many pixels which are over or underflowing, the correction factor α is decreased, wherein some filtering is applied at the feedback loop to avoid oscillations. The input image data can be filtered to detect a spatial correlation with respect to critical colors. The result of the first and second control unit CTRLl, CTRL2 is used to modulate the frame-based values of the correction factor and the gain factor. Fig. 9 shows a block diagram of a color gamut mapping unit according to a sixth embodiment. The color gamut mapping unit according to the sixth embodiment substantially corresponds to the color gamut mapping unit according to the fifth embodiment. However, an additional offset unit OU and a third control unit CTRL3 is provided. The estimated reduction of the image quality can be represented by the correction factor α, the gain factor β and the offset factor χ. The values of the factors will be dependent on the potential clipping artifacts of a pixel in an image. For each new image, the values of the factors are determined and are used for an adaptive contrast boosting as well as a color gamut mapping. V₀Ut = (1+β) * {[McGM]*V_m*(α)+V_m*(l-X)} - χ

= [M_CGM]*V_m*(l+β) * (α) + V_1n * (1+ β) * (1-α) - χ = {[M_CGM]*V_m*(α/(l-α)) + V_1n)* (1+ β) * (1- α) - χ

If no clipping occurs, the images are completely corrected by means of a color gamut mapping. Additionally, the contrast can be improved. If a significant underflow clipping occurs, the offset factor χ is reduced. If a significant overflow clipping occurs, first of all the offset factor β is reduced. Thereafter, if the clipping remains, also the correction factor α is reduced.

The above described principles of the invention (i.e. the adaptive color gamut mapping) may be used to compress the gamut for mobile displays. On the other hand, the gamut may be expanded for white gamut LCD television systems. The color space for multi- primary displays can be modified. Moreover, user settings like saturation, color temperature or the like can be executed and a picture enhancement, e.g. a blue stretch, green stretch can be achieved.

The above described adaptive color gamut mapping can be used to enhance color settings for display with limited color capabilities by performing a gamut compression. For mobile LCD displays which require a minimum power dissipation, limited colors are provided as the color spectrum of the backlight and the limited thickness and transmission of color filters are present. Moreover, mobile LCD displays only enable a poor performance with respect to contrast and bit depth such that color gamut mapping is performed without using an adaptive branch which reduces the required hardware while introducing artefacts.

PLED/OLED displays have limited colors because of the degradation of materials with optimal primary colors. Therefore, a preferred spectrum of primaries will be exchanged for a maximum life time. LCD front projection displays also may have limited colors due to the color spectrum of the light source as well as due to limited thickness and transmission of the color filters.

The white point of bright displays may correspond to the maximum output of the RGB but may not correspond to the D65 white point. In the case of very bright pixels, the white point should be corrected as the correction may result in a reduced luminance.

However, for less bright pixels, the white point can be corrected while still maintaining a correct luminance. According to an embodiment, a switch between predefined white point settings (e.g. cool (8500K), normal (D65) and warm (5000K)) can be performed. For a gamut expansion, i.e. a wide and bright gamut, the adaptive color gamut mapping can improve the color settings of such devices. LCD-TV displays may have a wide gamut color because of the color spectrum of the backlight combined with their color filters. The displays also may comprise a white sub-pixel to enhance the brightness and efficiency. The adaptive color gamut mapping may be used to reshape the color space accordingly supporting a bright gamut color. The adaptive color gamut mapping can be used to prevent clipping artefacts during a rendering process.

In case of multi-primary displays, the adaptive color gamut mapping may be used to enhance the color settings of displays with white gamut color capabilities as such displays may comprise an extra primary color to enhance the gamut and support an efficient use of the backlight spectrum. Adaptive color gamut mapping may be used to reshape the color space supporting bright gamut colors. The adaptive color gamut mapping may be used to prevent clipping artefacts during the rendering process.

On the other hand, user settings may be implemented by the adaptive color gamut mapping such that the personal preferences of a user can be used for the setting of the display. This may be performed by modifying the input coefficients of the sRGB input gamut to user specific coefficients which may describe a modified gamut before it is used in the mapping process. The mapping process may be used to map the 3D input gamut to a 3D output gamut wherein an input image appears with the user preferred saturation brightness, hue and whitepoint setting.

Furthermore, an image enhancement can be performed by the adaptive color gamut mapping. By means of additional adaptive processes, analyzing properties of the input pixel and depending on their location in the 3D color space with respect to hue, saturation and brightness, these pixels are mapped to a different location with a different hue, saturation and brightness. Accordingly, the input image may appear differently on a display as e.g. some green colors are getting more saturation, some skin-tone colors are getting a more ideal hue, bright white colors are getting a white-point towards blue and dark colors are getting less luminance and more saturation.

The above described color gamut mapping can be used in any display devices to enhance the front-of-screen performance. The adaptive color gamut mapping may also be embodied in display drivers or display modules. Alternatively or in addition, the above described adaptive color gamut mapping algorithm may be implemented in a companion chip. This is advantageous as only a limited amount of additional hardware is required to perform the respective algorithm. In addition or alternatively, the adaptive color gamut mapping algorithm may also be executed in software on a programmable processing device. Such a software algorithm may run on an ARM platform or on a media processor like Trimedia.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps other than those listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. In the device claim enumerating several means, several of these means can be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Furthermore, any reference signs in the claims shall not be constrained as limiting the scope of the claims.

Claims

CLAIMS:

1. Video processing device comprising: a color gamut mapping matrix unit (CGMM, ACGMM) for providing a color gamut mapping correction of an input signal; a mixing unit (MU) for applying a mix of color gamut mapped signal and the input signal, based on a first correction factor (α) by mixing properties of the color gamut mapped input pixels with properties of the input pixel corrected by the first correction factor (α); a clipping unit (CLU) for clipping properties of pixels of an output of the mixing unit (MU) if these properties are not within a predefined range; and - a first control unit (CTRLl) for determining the first correction factor (α) based on the amount of over- and/or under- flowing of the pixels outputted from the mixing unit (MU).

2. Video processing device according to claim 1, further comprising: - a luminance, saturation and hue detection and modulation unit (LSH) for providing for each pixel a new set of maxtrix coefficients towards the color gamut mapping matrix unit (ACGMM), depending on the luminance, saturation and hue properties of the pixel; wherein the color gamut mapping matrix unit (ACGMM) is adapted to provide an adaptive color gamut mapping correction.

3. Video processing device according to claim 1 or 2, further comprising: a spatial filter unit (SF) for providing data towards the first control unit

(CTRLl) depending on the spatial correlation properties of the input frame of input data; - wherein the first control unit (CTRLl) is adapted to determine a first correction factor (α) based on the amount of over- and/or under- flowing of the pixels (CU) outputted from the mixing unit (MU) as well as based on spatial correlation properties of the input frame, wherein the color gamut mapping matrix unit (CGMM) is adapted to provide an static color gamut mapping correction.

4. Video processing device according to claim 1, 2 or 3, further comprising: - an amplifying unit (AU) for amplifying properties of output pixels; and a second control unit (CTRL2) for determining a second correction factor (β) based on the amount of over- or under- flowing of the pixels (CU) outputted from the mixing unit (MU), wherein the amplifying unit (AU) is adapted to amplify properties of the output pixels according to the second correction factor (β).

5. Video processing device according to claim 4, further comprising: an offset unit (OU) for adding an offset to properties of the output pixels; and a third control unit (CTRL3) for determining a third correction factor (χ) based on the amount of over- or under- flowing of the pixels (CU) outputted from the mixing unit (MU), wherein the offset unit (OU) is adapted to add an offset to properties of the output pixels according to the third correction factor (χ).

6. Method of color gamut mapping in a video processing device, comprising the steps of: providing a color gamut mapping correction of an input signal by means of a color gamut mapping matrix, applying a mix of color gamut mapped signals and the input signals based on a first correction factor (α) by mixing properties of the color gamut mapped input pixels with properties of the input pixels corrected by the first correction factor (α).