Image Processing Process Applied to Colony Counters in Microbiology

Abstract

A method and device for counting colonies in a sample in a medium. A bright field image is generated from light transmitted through the sample and the medium in a bright field configuration and collected by a detection unit, and a dark field image is generated from light scattered from the sample and the medium in a dark field configuration and collected by a detection unit. A fusion image is generated by a computer processing unit by combining two operand images, one an inverted image of the bright field image, and the other the dark field image. Colonies of the sample are counted by the computer processing unit based on processing of the fusion image. A single detection unit can generate the bright and dark field images, or the detection units can be separate. Light and dark diffusing surfaces can be separately retained or formed by a single diffuser.

What is claimed as deserving the protection of Letters Patent: 
     
         1 . A method of counting colonies present in a sample placed in a support arranged to receive the sample and a solid nutrient medium, the method comprising:
 generating a bright field image from light transmitted through the sample and the medium in a bright field configuration and collected by a detection unit;   generating a dark field image from light scattered from the sample and the medium in a dark field configuration and collected by a detection unit;   generating a fusion image by a computer processing unit, the fusion image obtained by combining two operand images, wherein one of the operand images is an inverted image of the bright field image and the other operand image is the dark field image or one of the operand images is an inverted image of the dark field image and the other operand image is the bright field image;   counting colonies of the sample by the computer processing unit based on a processing of the fusion image.   
     
     
         2 . The method of  claim 1 , wherein the step of generating the fusion image comprises the linear combination of the two operand images. 
     
     
         3 . The method of  claim 2 , wherein the combination of the two operand images is performed by addition. 
     
     
         4 . The method of  claim 1 , wherein the processing of the fusion image comprises a thresholding of the fusion image from a predetermined threshold. 
     
     
         5 . An image processing device for counting colonies present in a sample, the device provided with a location adapted to receive a support arranged to receive a solid nutrient medium and the sample, wherein the image processing device comprises:
 a detection unit arranged to generate a bright field image from light transmitted through the sample and the medium in a bright field configuration and collected by the detection unit;   a detection unit arranged to generate a dark field image from light scattered from the sample and the medium in a dark field configuration and collected by the detection unit;   a computer processing unit arranged to generate a fusion image, wherein the fusion image is obtained by combining two operand images, wherein one of the operand images is an inverted image of the bright field image and the other operand image is the dark field image or one of the operand images is an inverted image of the dark field image and the other operand image is the bright field image;   wherein the computer processing unit is further configured to count a number of colonies of the sample based on a processing of the fusion image.   
     
     
         6 . The image processing device of  claim 5 , wherein the detection unit arranged to generate a bright field image and the detection unit arranged to generate a dark field image comprise a single detection unit. 
     
     
         7 . The image processing device of  claim 5 , wherein the detection unit arranged to generate a bright field image comprises a first detection unit and wherein the detection unit arranged to generate a dark field image comprises a second detection unit. 
     
     
         8 . The image processing device of  claim 5 , further comprising a light diffusing surface and a bright field light source for establishing the bright field configuration and a dark diffusing surface and a dark field light source for establishing the dark field configuration. 
     
     
         9 . The image processing device of  claim 8 , wherein the bright field light source comprises a first plurality of light emitting diodes and wherein the dark field light source comprises a second plurality of light emitting diodes. 
     
     
         10 . The image processing device of  claim 8 , wherein the computer processing unit is selectively operative to establish the bright field configuration wherein the dark field light source is extinguished and the bright field light source is illuminated to illuminate the medium and the sample with light diffused by the light diffusing surface and wherein the computer processing unit is selectively operative to establish the dark field configuration wherein the bright field light source is extinguished and the dark field light source is illuminated to illuminate the medium and the sample with light diffused by the dark diffusing surface. 
     
     
         11 . The image processing device of  claim 8 , wherein the light diffusing surface and the dark diffusing surface are formed by a single diffuser.