Digital image processing circuitry

Claim 2

Digital image processing circuitry for sharpening and transforming input electronic image data signals having a first tonescale and a first color coordinate system to output electronic image signals having a second tonescale and a second color coordinate system, having both luminance and chrominance components, the circuitry being characterized by: a) color processing means (10) for receiving the input electronic image data signals having a first tonescale and the first color coordinate system and transforming the input electronic image data signals into first intermediate electronic image data signals having a second tonescale and the second color coordinate system; b) sharpening means (24) for receiving the input electronic image data signals, differentiating between selected high and low spatial frequency components of the input electronic image data signals, and amplifying the selected high spatial frequency components of the input electronic image data signals to provide amplified high spatial frequency luminance signals; c) low pass filtering means (20) for receiving the first intermediate electronic image data signals and transmitting those spatial frequency components of the first intermediate electronic image data signals below at least one select spatial frequency to provide second intermediate electronic image data signals; and d) combining means (22) for combining the low spatial frequency luminance components of the second intermediate electronic image data signals with the amplified high spatial frequency luminance signals to provide sharpened luminance components which together with the chrominance components of the second intermediate electronic image data signals define the output electronic image data signals.

Claim 3

The circuitry according to claim 1 characterised in that the colour processing means (10) comprises: a) a first look up table (12) containing values indicative of a first tonescale transformation wherein the first look up table (12) receives the input electronic image data signals and provides tonescale matrixed corrected electronic image data signals; b) a first matrix (14) containing first colour coordinate transformation coefficients wherein the first matrix (14) receives the tonescale matrixed corrected electronic image data signals and provides first colour electronic image data signals; c) a second look up table (16) containing values indicative of a second tonescale transformation wherein the second look up table (16) receives the colour matrixed electronic image data signals and provides second tonescale corrected electronic image data signals; and d) a second matrix (18) containing second colour coordinate system transformation coefficients wherein second matrix (18) receives the second tonescale corrected electronic image data signals and provides the first intermediate electronic image data signals.

Claim 4

The circuitry according to claim 2, characterised in that the first tonescale transformation and the second tonescale transformation are selected from the group comprising a gamma function and an inverse gamma function.

Claim 5

The circuitry according to claim 1 characterised in that the colour processing means comprises a three dimensional look up table for receiving the input electronic image data signals having the first tonescale and the first colour coordinate system and for transforming the input electronic image data signals into first intermediate electronic image data signals having the second tonescale and the second colour coordinate system.

Claim 6

The circuitry according to any of the preceding claims, characterised in that the input electronic image data signals comprise a plurality of components for each pixel of the image being processed and wherein the sharpening means (24) comprises a) summation means (26) for receiving a select number of the components of the input electronic image data signals and for combining the components of the input electronic image data signals into composite electronic image data signals; b) first filtering means (28,32) for transmitting those spatial frequency components of the composite electronic image data signals above a select spatial frequency to provide only high spatial frequency signals associated with the composite electronic image data signals; c) variance circuit (30) for receiving the composite electronic image data signals and for providing variance signals therefrom which are indicative of the statistical variance of the composite electronic image data signals for a select group of pixels surrounding each pixel to be enhanced; d) a third look up table (36) containing values indicative of a plurality of adaptive amplification factors which vary as a function of different values of variance signals so as to distinguish between noise and signal information wherein the third look up table (36) receives and transforms the variance signals to adaptive amplification factor signals; e) second combining means (34) for combining the high spatial frequency signals and the adaptive amplification factor signals to provide adaptively amplified high spatial frequency signals; and f) a fourth look up table (38) containing values indicative of a plurality of pre-compensation factors which vary as a function of the different values of the adaptively amplified high spatial frequency signals wherein the fourth look up table (38) receives and transforms the adaptively amplified high spatial frequency signals to compensated and adaptively amplified high spatial frequency signals which define the amplified high spatial frequency luminance signals.

Claim 7

The circuitry according to claim 5 characterised in that the first filtering means (28, 32) comprises a) a low pass filter (28) for receiving the composite electronic image data signals and transmitting those spatial frequency components of the composite electronic image data signals below a selected spatial frequency to provide low spatial frequency signals associated with the composite electronic image data signals; and b) combining means (32) for transmitting those spatial frequency components of the composite electronic image data signals above the low spatial frequency signals to provide high spatial frequency signals associated with the composite electronic image data signals.

Claim 8

The circuitry according to any of the preceding claims, characterised in that the first intermediate electronic image data signals are comprised of both luminance components and chrominance components, the low pass filtering means (20) further comprising: a) first low pass filtering means for receiving the luminance components of the first intermediate electronic image data signals and transmitting those spatial frequency components of the luminance components of the first intermediate electronic image data signals below a first selected spatial frequency to provide luminance components of the second intermediate electronic image data signals; and b) second low pass filtering means for receiving the chrominance components of the first intermediate electronic image data signals and transmitting those spatial frequency components of the chrominance components of the first intermediate electronic image data signals below a second selected spatial frequency to provide chrominance components of the second intermediate electronic image data signals.

Claim 9

The circuitry according to any of claims 1 to 6, characterised in that the first intermediate electronic image data signals are comprised of luminance components, first chrominance components, and second chrominance components, the low pass filtering means (20) further comprising: a) first low pass filtering means for receiving the luminance components of the first intermediate electronic image data signals and transmitting those spatial frequency components of the luminance components of the first intermediate electronic image data signals below a first selected spatial frequency to provide luminance components of the second intermediate electronic image data signals; b) second low pass filtering means for receiving first chrominance components of the first intermediate electronic image data signals and transmitting those spatial frequency components of the first chrominance components of the first intermediate electronic image data signals below a second selected spatial frequency to provide first chrominance components of the second intermediate electronic image data signals; and c) third low pass filtering means for receiving the second chrominance components of the first intermediate electronic image data signals and transmitting those spatial frequency components of the second chrominance components of the first intermediate electronic data signals below a third selected spatial frequency to provide second chrominance components of the second intermediate electronic image data signals.

Claim 10

The circuitry according to any one of the preceding claims characterised in that the input electronic image data signals are colour space signals and the output electronic image data signals are a luminance signal and a pair of chrominance signals.