Automatic image object identification using threshold gradient magnitude based on terrain type

A method for automatically identifying objects in a first image comprising:

• identifying terrain types in the first image;
• generating, in a processor of a computer processing device, a second image identifying areas of the first image which border regions of different intensities by identifying a gradient magnitude value for each pixel of the first image;
• generating, in the processor, a filtered image from the second image, the filtered image identifying potential objects which have a smaller radius than the size of a filter and a different brightness than background pixels surrounding the potential objects;
• comparing, in the processor, the second image and the filtered image to identify potential objects as an object, a potential object is identified as an object if the potential object has a gradient magnitude greater than a threshold gradient magnitude, and the threshold gradient magnitude is based on the terrain type identified in the portion of the first image where the potential object is located;
• and
• generating a mean local gradient magnitude image using the second image, wherein the threshold gradient magnitude is determined using the mean local gradient magnitude image.

A method for automatically identifying objects in a first image comprising:

• identifying terrain types in the first image;
• generating, in a processor of a computer processing device, a second image identifying areas of the first image which border regions of different intensities by identifying a gradient magnitude value for each pixel of the first image;
• generating, in the processor, a filtered image from the second image, the filtered image identifying potential objects which have a smaller radius than the size of a filter and a different brightness than background pixels surrounding the potential objects;
• comparing, in the processor, the second image and the filtered image to identify potential objects as an object, a potential object is identified as an object if the potential object has a gradient magnitude greater than a threshold gradient magnitude, and the threshold gradient magnitude is based on the terrain type identified in the portion of the first image where the potential object is located,
• wherein the step of generating a filtered image comprises:
• performing a series of dilations and erosions of the second image to produce a spatially filtered image;
• and
• subtracting said spatially filtered image from the first image to produce the filtered image.

A non-transitory computer-readable recording medium having a computer program recorded thereon that causes a computer to identify objects in a first image, the program causing the computer to perform operations comprising:

• identifying terrain types in the first image;
• generating a second image identifying areas of the first image which border regions of different intensities by identifying a gradient magnitude value for each pixel of the first image;
• generating a filtered image from the second image, the filtered image identifying potential objects which have a smaller radius than the size of a filter and a different brightness than background pixels surrounding the potential objects;
• and
• comparing the second image and the filtered image to identify potential objects as an object, a potential object is identified as an object if the potential object has a gradient magnitude greater than a threshold gradient magnitude, and the threshold gradient magnitude is based on the terrain type identified in the portion of the first image where the potential object is located.

A non-transitory computer-readable recording medium having a computer program recorded thereon that causes a computer to identify objects in a first image, the program causing the computer to perform operations comprising:

• identifying terrain types in the first image;
• generating a second image identifying areas of the first image which border regions of different intensities by identifying a gradient magnitude value for each pixel of the first image;
• generating a filtered image from the second image, the filtered image identifying potential objects which have a smaller radius than the size of a filter and a different brightness than background pixels surrounding the potential objects;
• comparing the second image and the filtered image to identify potential objects as an object, a potential object is identified as an object if the potential object has a gradient magnitude greater than a threshold gradient magnitude, and the threshold gradient magnitude is based on the terrain type identified in the portion of the first image where the potential object is located;
• and
• generating a mean local gradient magnitude image using the second image, wherein the threshold gradient magnitude is determined using the mean local gradient magnitude image.

A non-transitory computer-readable recording medium having a computer program recorded thereon that causes a computer to identify objects in a first image, the program causing the computer to perform operations comprising:

• identifying terrain types in the first image;
• generating a second image identifying areas of the first image which border regions of different intensities by identifying a gradient magnitude value for each pixel of the first image;
• generating a filtered image from the second image, the filtered image identifying potential objects which have a smaller radius than the size of a filter and a different brightness than background pixels surrounding the potential objects;
• and
• comparing the second image and the filtered image to identify potential objects as an object, a potential object is identified as an object if the potential object has a gradient magnitude greater than a threshold gradient magnitude, and the threshold gradient magnitude is based on the terrain type identified in the portion of the first image where the potential object is located,
• wherein the operation of generating a filtered image comprises:
• performing a series of dilations and erosions of the second image to produce a spatially filtered image;
• and
• subtracting said spatially filtered image from the first image to produce the filtered image.