Automatic background removal for input data

Abstract

Automatic background signal removal for input data, such as for spectrometry data, is provided. Input data includes input pixel points, such as those read by a CCD spectrometer of chromatography device, and intensity values corresponding to the data points. A distribution of changes in the intensity values between the data points is determined, and a noise level is judged by setting a threshold for the distribution. A noise region is identified as a predetermined number of consecutive input points for which the changes in the intensity values are within the noise level. Adjacent noise regions may be connected and the background signal is thus determined and subtracted. A spike noise region may also be identified and filtered, such that a peak obtained from fewer than a second predetermined number of the pixel points is determined as a spike, not a true peak. Non-spike large amplitude noises are optionally filtered.

1 . A background removal method, comprising: 
 inputting input data comprising input points and intensity values corresponding to the input points;    determining a distribution of changes in the intensity values between the input points and judging a noise level for the input data according to a threshold for the distribution;    identifying noise regions of the input data by identifying a predetermined number of consecutive input points for which the changes in the intensity values are within the noise level;    subtracting background from the input data based on the identified noise regions; and    outputting as the target sample signal the background removed data.    
   
   
       2 . The method of  claim 1 , wherein the input data are one of spectral data obtained from a spectrometer and chromatography data.  
   
   
       3 . The method of  claim 1 , wherein an absolute value of the change in the intensity value is determined as the change in the intensity value and wherein the noise level is judged based on the absolute values of the changes in the intensity values below the threshold.  
   
   
       4 . The method of  claim 3 , wherein one of an average, a median, a mode, a mean, and a range of the absolute values of the changes in the intensity values is determined for the values of the distribution above the threshold.  
   
   
       5 . The method of  claim 1 , wherein a spike noise region is identified as a peak obtained from fewer than a second predetermined number of the input points.  
   
   
       6 . The method of  claim 1 , wherein the noise regions and line segments connecting adjacent noise regions are interpreted as the background.  
   
   
       7 . The method of  claim 1 , wherein the input data are processed by at least one of normalizing and smoothing prior to the determining of the distribution.  
   
   
       8 . The method of  claim 7 , wherein the background is determined for smoothed input data and subtracted from unsmoothed input data.  
   
   
       9 . The method of  claim 1 , wherein a spike noise region is identified and filtered, such that a peak obtained from fewer than a second predetermined number of consecutive input points is determined as a spike.  
   
   
       10 . The method of  claim 1 , wherein a spike noise region is identified as a peak in which at least one of a second data point and a penultimate data point corresponds to a highest intensity point of that peak.  
   
   
       11 . The method of  claim 1 , wherein a spike noise region is identified as a peak region with at least two peak points within a predetermined number of consecutive data points.  
   
   
       12 . The method of  claim 11 , wherein the predetermined number of consecutive data points is five.  
   
   
       13 . A background removal system, comprising: 
 an input data receiver configured to receive input data comprising input points and intensity values corresponding to the input points;    a noise level setter configured to determine a distribution of changes in the intensity values between input points and to judge a noise level for the input data according to a threshold for the distribution;    a noise region identifier configured to identify noise regions of the input data by identifying a predetermined number of consecutive input points for which the changes in the intensity values are within the noise level;    a background remover configured to subtract background from the input data based on the identified noise regions; and    a data output configured to output as the target sample signal the background removed data.    
   
   
       14 . The system of  claim 13 , wherein the input data are one of spectral data obtained from a spectrometer and chromatography data.  
   
   
       15 . The system of  claim 13 , wherein an absolute value of the change in the intensity value is determined as the change in the intensity value and wherein the noise level is judged based on the absolute values of the changes in the intensity below the threshold.  
   
   
       16 . The system of  claim 15 , wherein one of an average, a median, a mode, a mean, and a range of the absolute values of the changes in the intensity values is determined for the values of the distribution above the threshold.  
   
   
       17 . The system of  claim 13 , wherein a spike noise region is identified as a peak obtained from fewer than a second predetermined number of the input points.  
   
   
       18 . The system of  claim 13 , wherein the noise regions and line segments connecting adjacent noise regions are interpreted as the background.  
   
   
       19 . The system of  claim 13 , wherein the input data are processed by at least one of normalizing and smoothing prior to the determining of the distribution.  
   
   
       20 . The system of  claim 19 , wherein the background is determined for smoothed input data and subtracted from unsmoothed input data.  
   
   
       21 . The system of  claim 13 , wherein a spike noise region is identified and filtered, such that a peak obtained from fewer than a second predetermined number of consecutive input points is determined as a spike.  
   
   
       22 . The system of  claim 13 , wherein a spike noise region is identified as a peak in which at least one of a second data point and a penultimate data point corresponds to a highest intensity point of that peak, and the spike noise region is filtered.  
   
   
       23 . The system of  claim 13 , wherein a spike noise region is identified as a peak region with at least two peak points within a predetermined number of consecutive data points.  
   
   
       24 . The system of  claim 23 , wherein the predetermined number of consecutive data points is five.  
   
   
       25 . A processor readable medium embodying a background removal program of instructions comprising: 
 input data receiver means for receiving input data comprising input points and intensity values corresponding to the input points;    noise level setter means for determining a distribution of changes in the intensity values between input points and for judging a noise level for the input data according to a threshold for the distribution;    noise region identifier means for identifying noise regions of the input data by identifying a predetermined number of consecutive input points for which the changes in the intensity values are within the noise level;    background removal means for subtracting background from the input data based on the identified noise regions; and    data output means for outputting as the target sample signal the background removed data.    
   
   
       26 . The medium of  claim 25 , wherein the input data are one of spectral data obtained from a spectrometer and chromatography data.  
   
   
       27 . The medium of  claim 25 , wherein an absolute value of the change in the intensity value is determined as the change in the intensity value and wherein the noise level is judged based on the absolute values of the changes in the intensity values below the threshold.  
   
   
       28 . The medium of  claim 25 , wherein one of an average, a median, a mode, a mean, and a range of the absolute values of the changes in the intensity values is determined for the values of the distribution above the threshold.  
   
   
       29 . The medium of  claim 25 , wherein a spike noise region is identified as a peak obtained from fewer than a second predetermined number of the input points.  
   
   
       30 . The medium of  claim 25 , wherein the noise regions and line segments connecting adjacent noise regions are interpreted as the background.  
   
   
       31 . The medium of  claim 25 , wherein the input data are processed by at least one of normalizing and smoothing prior to the determining of the distribution.  
   
   
       32 . The medium of  claim 31 , wherein the background is determined for smoothed input data and subtracted from unsmoothed input data.  
   
   
       33 . The medium of  claim 25 , wherein a spike noise region is identified and filtered, such that a peak obtained from fewer than a second predetermined number of consecutive input points is determined as a spike.  
   
   
       34 . The medium of  claim 25 , wherein a spike noise region is identified as a peak in which at least one of a second data point and a penultimate data point corresponds to a highest intensity point of that peak.  
   
   
       35 . The medium of  claim 25 , wherein a spike noise region is identified as a peak region with at least two peak points within a determined number of consecutive data points.  
   
   
       36 . The medium of  claim 35 , wherein the predetermined number of consecutive data points is five.