Encoding and decoding the spectral distribution of light
AssigneeIntelligent Vision GmbH
InventorsArnold Giske, Fedja Bobanovic
Life of this patent
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Abstract
The particular spectral distribution of light is encoded to a spectral distribution identifier. The light is separately filtered by a set of filters, that together comply with conditions, such as uniqueness and/or efficiency conditions. The filtered light is measured to obtain a provisional intensity vector. To compensate for variations, computing functions use an intensity reference value to accommodate light variations and use pre-determined calibration data to accommodate filter variations. The computing functions thereby turn the provisional intensity vector to the spectral distribution identifier.
Claims20
Method to encode a spectral distribution of light into a spectral distribution identifier, wherein the light has a wavelength-specific intensity (Ak, [A]) in the spectral distribution within a wavelength range, from a minimum wavelength (λ_min) to a maximum wavelength (λ_max) with a wavelength resolution (Δλ), the method comprising:
- receiving the light to obtain received light;
- filtering the received light by a filter set of at least N=3 filters by each filter of the filter set separately, to thereby obtain filtered light, wherein the filter set complies with:
- (1) each filter in the filter set has a filter-specific transmission function (Tn) describing a wavelength-specific (k) transmission (Tnk) of the filter,
- (2) in a combined transmission function ({T}) for the filter set, a concatenation ({T}k) of the transmissions (TnK) define a transmission vector ({T}k) that is unique for any wavelength (k) and is unique for each spectral distribution in the wavelength range,
- (3) each filter in the filter set is a single-state filter;
- for each of the N filters separately, measuring an intensity of the filtered light over the wavelength range to obtain provisional intensity values (Bn) as N elements of a provisional intensity vector ({B}, 230-n);
- and
- providing a spectral distribution identifier with N elements that encodes the spectral distribution of the light based on an intensity reference value (L_DATA) to accommodate light variations and on pre-determined calibration data ({CAL}) to accommodate filter variations,
- wherein providing the spectral distribution identifier includes processing the provisional intensity values (Bn) of the provisional intensity vector ({B}) using the pre-determined calibration data ({CAL}) and the intensity reference value (L_DATA) to obtain normalized and calibrated intensity values (Dn) as elements of a normalized and calibrated intensity vector ({D}) so that the spectral distribution identifier is provided as the normalized and calibrated intensity vector ({D}).
A device adapted to encode a spectral distribution of light, the device comprising a filter layer that is attached to a sensor layer, wherein the filter layer and the sensor layer are planar layers,
- wherein the filter layer is adapted to receive light on its surface (XY) to obtain received light, and to transmit the received light to the sensor layer,
- wherein the filter layer and the sensor layer are divided into disjunct pixel locations that correspond to filter locations and that correspond to sensors,
- wherein the sensors are adapted to quantify the intensity (A) of the transmitted light by integrating it during a measurement time interval to provide sensor-specific provisional intensity values (Bn, LUMINANCE) that represent forwarded light;
- wherein for a contiguous combination of M pixel locations defining an area, the following applies, for N<M:
- N filter locations hold a filter set of N≥3 filters above the corresponding sensors, so that the corresponding sensors provide the sensor-specific intensity values as provisional intensity values (Bn),
- M-N filter locations are either empty or hold filters with a wavelength non-specific transmission function, so that the corresponding sensors provide the sensor-specific intensity values as luminance values (LUMINANCE);
- wherein each of the N filters in the filter set has a filter-specific transmission function (Tn) describing a wavelength-specific (k) transmission (Tnk) of the filter, and wherein in a combined transmission function ({T}) for the filter set, the concatenation ({T}k) of the transmissions (TnK) define a transmission vector ({T}k) that is unique for any wavelength (k) and is unique for each spectral distribution of light in the wavelength range,
- wherein the device is configured to process the provisional intensity values (Bn) to normalized intensity values (Dn) being the elements of a normalized intensity vector ({D}) that corresponds to a spectral distribution identifier encoding the particular spectral distribution of the received light.
A computer program product storing instructions, which, when loaded into a memory of a computer and executed by at least one processor of the computer, cause the computer to encode a spectral distribution of light into a spectral distribution identifier, wherein the light has a wavelength-specific intensity (Ak, [A]) in the spectral distribution within a wavelength range, from a minimum wavelength (λ_min) to a maximum wavelength (λ_max) with a wavelength resolution (Δλ), including causing the computer to:
- receive the light to obtain received light;
- filter the received light by a filter set of at least N=3 filters by each filter of the filter set separately, to thereby obtain filtered light, wherein the filter set complies with:
- (1) each filter (120-n) in the filter set has a filter-specific transmission function (Tn) describing a wavelength-specific (k) transmission (Tnk) of the filter,
- (2) in a combined transmission function ({T}) for the filter set (120), a concatenation ({T}k) of the transmissions (TnK) define a transmission vector ({T}k) that is unique for any wavelength (k) and is unique for each spectral distribution in the wavelength range,
- (3) each filter in the filter set is a single-state filter;
- for each of the N filters separately, measure an intensity of the filtered light over the wavelength range to obtain provisional intensity values (Bn) as N elements of a provisional intensity vector ({B}, 230-n);
- and
- provide a spectral distribution identifier with N elements that encodes the spectral distribution of the light based on an intensity reference value (L_DATA) to accommodate light variations and on pre-determined calibration data ({CAL}) to accommodate filter variations,
- wherein providing the spectral distribution identifier includes processing the provisional intensity values (Bn) of the provisional intensity vector ({B}) using the pre-determined calibration data ({CAL}) and the intensity reference value (L_DATA) to obtain normalized and calibrated intensity values (Dn) as elements of a normalized and calibrated intensity vector ({D}) so that the spectral distribution identifier (250) is provided as the normalized and calibrated intensity vector ({D}).
Dependencies are inferred from the claim text.