Method for enhancing image quality by saturation
View Patent ↗The present invention relates to a method for enhancing an image quality by saturation. The method includes the step of: determining a minimum gain value ‘SatGainMin’ and a maximum gain value ‘SatGainMax’ of a gain value ‘PGain’ of a pre-amplifier; defining a first to a third ranges based on the ‘SatGainMin’ and the ‘SatGainMax’; determining whether a currently used saturation value ‘USat’ is equal to or greater than approximately 1; determining whether the ‘PGain’ is less than the ‘SatGainMin’; performing saturation by using a value in the first range as an actual saturation value ‘ASat’ when ‘PGain’< ‘SatGainMin’; determining whether the ‘PGain’ is equal to or less than the ‘SatGainMax’; performing saturation by using a value in the second range as the ‘ASat’ when ‘SatGainMin’≦‘PGain’≦‘SatGainMax’; and performing saturation by using a value in the third range as the ‘ASat’ when ‘PGain’>‘SatGainMax’.
1. A method for enhancing an image quality by changing a saturation value through converting analog signals outputted from an pixel array of an image sensor into digital signals and then multiplying a saturation value set by a user with signal values ‘Cr’ and ‘Cb’ except for a brightness component ‘Y’ among the digital signals, wherein the analog signals which are weak are divided into a first to a third ranges based on a minimum gain value ‘SatGainMin’ and a maximum gain value ‘SatGainMax’ of a gain value ‘PGain’ of a pre-amplifier for amplifying the analog signals through changing a gain per brightness level, the method is carried out by a saturation suppression block to perform the following steps:
using N which is a positive integer as an actual saturation value ‘ASat’ in the first range where the ‘PGain’ is less than the ‘SatGainMin’;
using M which is a positive integer equal to or less than the N as the ‘ASat’ in the third range where the ‘PGain’ is greater than the ‘SatGainMax’; and
using a value of a linear function with a slope decreasing linearly from the N to the M as the ‘ASat’ in the second range where the ‘PGain’ is equal to or greater than the ‘SatGainMin’ and equal to or less than the ‘SatGainMax’.
2. The method of claim 1 , wherein a currently used saturation value ‘USat’ in the first range to the third range is equal to or greater than approximately 1.
3. The method of claim 2 , wherein the N in the first range is the ‘USat’.
4. The method of claim 3 , wherein the M in the third range is approximately 1.
5. The method of claim 4 , wherein the value of the linear function used as the ‘ASat’ in the second range is defined as:
USat
-
{
(
USat
-
1
)
×
(
PGain
-
SatGainMin
)
(
SatGainMax
-
SatGainMin
)
}
.
6. The method of claim 1 , wherein the image has a low level of brightness going from the first range to the third range.
7. A method for enhancing an image by changing a saturation value through converting analog signals outputted from an pixel array of an image sensor into digital signals and then multiplying a saturation value set by a user with signal values ‘Cr’ and ‘Cb’ except for a brightness component ‘Y’ among the digital signals, the method a saturation suppression block to perform the following steps:
determining a minimum gain value ‘SatGainMin’ and a maximum gain value ‘SatGainMax’ of a gain value ‘PGain’ of a pre-amplifier for amplifying the analog signals through changing a gain per brightness level because the analog signals are weak;
defining a first to a third ranges based on the ‘SatGainMin’ and the ‘SatGainMax’ of the ‘PGain’;
determining whether a currently used saturation value ‘USat’ is equal to or greater than approximately 1;
determining whether the ‘PGain’ is less than the ‘SatGainMin’ upon the determination that the ‘USat’ is equal to or greater than approximately 1;
performing saturation by using a value corresponding to the first range as an actual saturation value ‘ASat’ when the ‘PGain’ is less than the ‘SatGainMin’;
determining whether the ‘PGain’ is equal to or less than the ‘SatGainMax’ when the ‘PGain’ is equal to or greater than the ‘SatGainMin’;
performing saturation by using a value corresponding to the second range as the ‘ASat’ when the ‘PGain’ is equal to or greater than the ‘SatGainMin’ and equal to or less than the ‘SatGainMax’; and
performing saturation by using a value corresponding to the third range as the ‘ASat’ when the ‘PGain’ is greater than the ‘SatGainMax’.
8. The method of claim 7 , wherein a suppression saturation operation is not performed when the ‘USat’ is less than approximately 1.
9. The method of claim 7 , wherein the ‘ASat’ in the first range is N which is a positive integer; the ‘ASat’ in the third range is M which is a positive integer equal to or less than the N; and the ‘ASat’ in the second range is a value of a linear function with a slope decreasing linearly from the N to the M.
10. The method of claim 9 , wherein the N is the ‘USat’.
11. The method of claim 10 , wherein the M is approximately 1.
12. The method of claim 11 , wherein the linear function used in the second range is defined as:
ASat
=
USat
-
{
(
USat
-
1
)
×
(
PGain
-
SatGainMin
)
(
SatGainMax
-
SatGainMin
)
}
.
13. The method of claim 12 , wherein the image has a low level of brightness going from the first range to the third range.