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1. WO2020117260 - IMAGED TRANSMISSION PERCENTAGES FOR 3D PRINTERS

Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters

[ EN ]

CLAIMS

1. An apparatus, comprising:

a light table to hold an object;

a camera to capture images, wherein the light table is positioned within a field of view of the camera; and

a processor communicatively coupled to the camera to receive the images, wherein the processor is to analyze the images to calculate an imaged transmission percentage at a plurality of different locations of the object based on a correlation function of the camera used to determine an amount of print agents to be dispensed by a three dimensional printer to print the object.

2. The apparatus of claim 1 , wherein the camera comprises a red, green, blue (RGB) camera or a monochromatic camera.

3. The apparatus of claim 1 , wherein the images comprise an image of the light table, an image of the light table with the object, and an image of the light table with a standardized transmission chart.

4. The apparatus of claim 3, further comprising:

a tele-spectrophotometer to measure a luminance value of different locations on the standardized transmission chart.

5. The apparatus of claim 4, wherein the correlation function is based on a comparison of the luminance value of the different locations measured by the tele-spectrophotometer and luminance values of the different locations obtained from the image of the light table with the standardized transmission chart captured by the camera.

6. A method comprising:

receiving, by the processor, an image of an object on a light table and an image of the light table captured by the camera;

calculating, by the processor, an imaged transmission percentage of different locations of the object based on the image of the object on the light table, the image of the light table, and a correlation function of the camera; and programming, by the processor, a three dimensional printer to print the object based on the imaged transmission percentage of different locations of the object that is calculated.

7. The method of claim 6, further comprising:

calculating the correlation function of the camera, wherein the calculating comprises:

receiving, by the processor, an image of the light table with a standardized transmission chart to calculate luminance values of different locations of the standardized transmission chart;

receiving, by the processor, luminance values of the different locations of the standardized transmission chart on the light table from a tele-spectrophotometer; and

calculating, by the processor, the correlation function based on a comparison of the luminance values from the image and the luminance values from the tele-spectrophotometer.

8. The method of claim 7, wherein the luminance values are calculated from the image by converting red, green, blue (RGB) values of each pixel of the image at the different locations.

9. The method of claim 7, wherein the calculating the correlation function comprises performing a polynomial fit between the luminance values from the image and the luminance values from the tele-spectrophotometer.

10. The method of claim 6, wherein the calculating the imaged transmission percentage, comprises:

converting, by the processor, each pixel at the different locations of the image of the object on the light table and the image of the light table from red, green, blue (RGB) values into luminance values;

calculating, by the processor, absolute luminance values by applying the correlation function to the luminance values; and

dividing, by the processor, for each pixel a respective absolute luminance value from the image of the object on the light table by a respective absolute luminance value from the image of the light table.

1 1. The method of claim 6, wherein the programming the 3D printer, comprises:

correlating, by the processor, the imaged transmission percentage at a location of the different locations to an amount of printing agents;

dispensing, by the processor, the amount of print agents at the location to achieve a desired opacity; and

printing, by the processor, a portion of the object at the location to have the desired opacity.

12. A non-transitory computer readable storage medium encoded with instructions executable by a processor, the non-transitory computer-readable storage medium comprising:

instructions to calculate a correlation function of a red, green, blue (RGB) camera;

instructions to receive an image of an object on a light table and an image of the light table captured by the camera;

instructions to convert an RGB value of each pixel of the image of the object on the light table and the image of the light table to a luminance value; instructions to apply the correlation function to the luminance value to obtain an absolute luminance value;

instructions to calculate an imaged transmission percentage of a pixel based on a comparison of the absolute luminance value of the pixel in the image of the object on the light table to the absolute luminance value of the pixel in the image of the light table; and

instructions to control a three dimensional (3D) printer to print a portion of the object at a location that corresponds to the pixel based on the imaged transmission percentage of the pixel to obtain a desired opacity.

13. The non-transitory computer readable storage medium of claim 12, further comprising:

instructions to set the transmission percentage associated with the desired opacity to a reference transmission percentage, wherein a subsequently printed object is accepted when a transmission percentage of the subsequently printed object is within a threshold of the reference transmission percentage at a corresponding location.

14. The non-transitory computer readable storage medium of claim 12, wherein the instructions to calculate the correlation function of the RGB camera, comprises:

instructions to receive an image of the light table with a standardized transmission chart to calculate luminance values of different locations of the standardized transmission chart;

instructions to receive luminance values of the different locations of the standardized transmission chart on the light table from a tele

spectrophotometer; and

instructions to calculate the correlation function based on a comparison of the luminance values from the image and the luminance values from the tele spectrophotometer.

15. The non-transitory computer readable storage medium of claim 14, wherein the luminance values are calculated from the image by converting red, green, blue (RGB) values of each pixel of the image at the different locations.