Method for scaling channel of an image
View Patent ↗A method for scaling a first channel of an image. The method comprises computing a low resolution second channel of the image based on a transformation of the second channel with a transformation function used to transform a high resolution channel into a low resolution channel; computing a correlation function between the low resolution second channel and the first channel; determining a predicted second channel having the high resolution from the low resolution second channel according to a prediction method; computing a high-pass second channel based on the difference between the second channel and the predicted second channel and based on the correlation function; and determining a predicted first channel having the high resolution from the first channel according to the prediction method.
1. A method for scaling a first channel of an image, wherein the method comprises:
receiving the first channel and a second channel of the image, the first channel having a low resolution and the second channel having a high resolution;
computing a low resolution second channel based on a transformation of the second channel with a transformation function used to transform a channel having the high resolution into a channel having the low resolution;
computing a correlation function between the low resolution second channel and the first channel;
determining a predicted second channel having the high resolution from the low resolution second channel according to a prediction method;
computing a high-pass second channel based on the difference between the second channel and the predicted second channel and based on the correlation function;
determining a predicted first channel having the high resolution from the first channel according to the prediction method; and
determining a scaled first channel based on the predicted first channel and the high-pass second channel.
2. A method according to claim 1 , wherein the method further comprises:
modifying values of the correlation function based on the computation of a regression estimation.
3. A method according to claim 1 , wherein the method further comprises:
decreasing, clamping, or setting to zero at least one value of the correlation function if the at least one value is greater to a predetermined threshold.
4. A method according to claim 1 , wherein the first channel comprises points, each point having coordinates in a set of coordinates {(n,m)}, wherein the low resolution second channel comprises points, each point being in correspondence with a point of the first channel,
and wherein computing a correlation function between the low resolution second channel and the first channel comprises, for each point of coordinates (n,m) in the set {(n,m)}:
determining a subset of points having coordinates within a predetermined distance from the point of coordinates (n,m);
within said subset, computing a correlation value α(n,m) based on a correlation of variations of the low resolution second channel with variations of the first channel.
5. A method according to claim 4 , wherein the variations are computed according to a horizontal direction.
6. A device for scaling a first channel of an image, wherein the device comprises:
an input interface for receiving the first channel and a second channel of the image, the first channel having a low resolution and the second channel having a high resolution;
a circuit for computing a low resolution second channel based on a transformation of the second channel with a transformation function used to transform a channel having the high resolution into a channel having the low resolution;
a circuit for computing a correlation function between the low resolution second channel and the first channel;
a circuit for determining a predicted second channel having the high resolution from the low resolution second channel according to a prediction method;
a circuit for computing an high-pass second channel based on the difference between the second channel and the predicted second channel and based on the correlation function;
a circuit for determining a predicted first channel having the high resolution from the first channel according to the prediction method; and
a circuit for determining a scaled first channel based on the predicted first channel and the high-pass second channel.
7. A non-transitory computer readable storage medium for scaling a first channel of an image, having stored thereon a computer program comprising program instructions, the computer program being loadable into a data-processing unit and adapted to cause the data-processing unit to carry out the steps, when the computer program is run by the data-processing device;
receiving the first channel and a second channel of the image, the first channel having a low resolution and the second channel having a high resolution;
computing a low resolution second channel based on a transformation of the second channel with a transformation function used to transform a channel having the high resolution into a channel having the low resolution;
computing a correlation function between the low resolution second channel and the first channel;
determining a predicted second channel having the high resolution from the low resolution second channel according to a prediction method;
computing a high-pass second channel based on the difference between the second channel and the predicted second channel and based on the correlation function;
determining a predicted first channel having the high resolution from the first channel according to the prediction method; and
determining a scaled first channel based on the predicted first channel and the high-pass second channel.