Image Processing Method And System For 3D Printing

Abstract

An image processing method for 3D printing includes the steps of projecting an initial image on a layer to be printed; shifting the initial image in a first direction, wherein the initial image is shifted by a first distance from an initial position to a first limited position to obtain a first image, wherein the first distance is not greater than a length of one pixel of the initial image in the first direction; fusing the initial image and the first image together to obtain a fused image; and printing the fused image on the layer to be printed.

Claims

1-27. (canceled)

28. An image processing method for 3D printing, comprising the steps, executed by a computer, of: (a) projecting an initial image on a layer to be printed; (b) shifting said initial image in a first direction, wherein the initial image is shifted by a first distance from an initial position to a first limited position to obtain a first image, wherein said first distance is not greater than a length of one pixel of said initial image in the said direction; (c) fusing said initial image and said first image together to obtain a fused image; and (d) printing said fused image on said layer to be printed.

29. The image processing method, as recited in claim 28, wherein the step (c) further comprises a step of superimposing gray values of said pixels at said initial position and said first limited position of said initial image and said first image respectively.

30. The image processing method, as recited in claim 28, wherein, in the step (b), said initial image is shift one or more times in said first direction to obtain one or more of said first images, such that said one or more of said first images are fused with said initial image to obtain said fused image, wherein said first distances of said initial images are the same each time.

31. The image processing method, as recited in claim 28, wherein said first distance is half of a length of said pixel in said initial image in said first direction.

32. The image processing method, as recited in claim 28, wherein the step (b) further comprises a step of: (b.1) shifting said first image in a second direction, wherein said first image is shifted by a second distance from said first limited position to a second limited position to obtain a second image, wherein said first distance is perpendicular to said first direction, such that, in the step (c), said initial image, said first image and said second image are fused to obtain the fused image.

33. The image processing method, as recited in claim 32, wherein said second distance is not greater than a length of said pixel of said initial image in said second direction.

34. The image processing method, as recited in claim 32, wherein, in the step (b.1), said first image is shift one or more times in said second direction to obtain one or more of said second images, such that said one or more of said second images are fused with said initial image and said first image to obtain said fused image, wherein said second distances of said first images are the same each time.

35. The image processing method, as recited in claim 32, wherein said second distance is half of a length of said pixel in said initial image in said second direction.

36. The image processing method, as recited in claim 32, wherein the step (b.1) further comprises a step of: (b.1.1) shifting said second image in a third direction, wherein said second image is shifted by a third distance from said second limited position to a third limited position to obtain a third image, wherein said third distance is opposite to said first direction, such that, in the step (c), said initial image, said first image, said second image and said third image are fused to obtain the fused image.

37. The image processing method, as recited in claim 36, wherein said third distance is not greater than a length of said pixel of said initial image in said first direction.

38. The image processing method, as recited in claim 36, wherein, in the step (b.1.1), said second image is shift one or more times in said third direction to obtain one or more of said third images, such that said one or more of said third images are fused with said initial image, said first image and said second image to obtain said fused image, wherein said third distances of said first images are the same each time.

39. The image processing method, as recited in claim 36, wherein a number of said second image shifting in said third direction is the same as a number of said initial image shifting in said first direction.

40. The image processing method, as recited in claim 36, wherein said first distance is half of a length of said pixel in said initial image in said first direction, wherein said initial image shifting in said first direction at one time.

41. The image processing method, as recited in claim 40, wherein said second distance is half of a length of said pixel in said initial image in said second direction, wherein said first image shifting in said second direction at one time.

42. The image processing method, as recited in claim 41, wherein a distance between said first limited position and said third limited position in said first direction is zero.

43. An image processing arrangement for 3D printing, comprising: a processor; and a memory coupled to said processor, wherein said memory stores computer program instructions executed by said processor and configured to: project an initial image on a layer to be printed; shift said initial image in a first direction, wherein the initial image is shifted by a first distance from an initial position to a first limited position to obtain a first image, wherein said first distance is not greater than a length of one pixel of said initial image in the said direction; fuse said initial image and said first image together to obtain a fused image; and print said fused image on said layer to be printed.

44. The image processing arrangement, as recited in claim 43, wherein said processor is configured to: shift said first image in a second direction, wherein said first image is shifted by a second distance from said first limited position to a second limited position to obtain a second image, wherein said first distance is perpendicular to said first direction, such that said initial image, said first image and said second image are fused to obtain the fused image

45. The image processing arrangement, as recited in claim 44, wherein said processor is configured to: shift said second image in a third direction, wherein said second image is shifted by a third distance from said second limited position to a third limited position to obtain a third image, wherein said third distance is opposite to said first direction, such that said initial image, said first image, said second image and said third image are fused to obtain the fused image.

46. The image processing arrangement, as recited in claim 45, wherein said first distance is not greater than a length of said pixel of said initial image in said first direction, wherein said second distance is not greater than said length of said pixel of said initial image in said second direction, wherein said third distance is not greater than a length of said pixel of said initial image in said third direction.

47. The image processing arrangement, as recited in claim 46, wherein a distance between said first limited position and said third limited position in said first direction is zero.

Description

BRIEF DESCRIPTION OF THE DRAWING(S)

[0045] FIG. 1 is a schematic diagram of a grayscale of an image before shifting in one direction once according to a preferred embodiment of the present invention;

[0046] FIG. 2 is a schematic diagram of the grayscale overlay of the image after shifting in one direction once according to the preferred embodiment of the present invention;

[0047] FIG. 3 is a schematic diagram of the grayscale of the image before shifting in one direction twice according to the preferred embodiment of the present invention;

[0048] FIG. 4 is a schematic diagram of the grayscale overlay of the image after shifting in one direction twice according to the preferred embodiment of the present invention;

[0049] FIG. 5 is a schematic diagram of the grayscale of the image before shifting half a pixel according to the preferred embodiment of the present invention;

[0050] FIG. 6 is a schematic diagram of the grayscale overlay of the image after shifting half a pixel according to the preferred embodiment of the present invention;

[0051] FIG. 7 is a schematic diagram of the grayscale overlay according to the preferred embodiment of the present invention;

[0052] FIG. 8 is a schematic diagram of an image shifting process according to the preferred embodiment of the present invention;

[0053] FIG. 9 is a flowchart of using the image processing method to improve the accuracy of DLP 3D printing according to the preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0054] In the following description, for purpose of explanation, numerous specific details are set forth in order to provide a thorough understanding of some example embodiments. It will be evident, however, to one of ordinary skill in the art that embodiments of the present invention may be practiced without these specific details.

[0055] According to the present invention as shown in FIG. 1, an image is configured to shift from an initial position A to a first limited position B in a width direction of the image, wherein a shifting distance between point A and point B is not greater than a width of one pixel of the image. In FIG. 1, a and b refer to predetermined areas in the image before shifting, and b and c refer to the corresponding areas in the image after shifting. As shown in FIG. 1, before shifting, gray values of the image are a:G1, b:G1, c:G2. After overlaying the gray values of the images before and after shifting, area b is a gray-scale fusion area of the image, wherein the gray value of the area b is determined by adding the gray values of the two images before and after shifting at the corresponding positions, which is equal to G1+G2. As shown in FIG. 2, after shifting, the gray values are a:G1, b:G1+G2, c:G2. In other words, after shifting once, the gray value of the initial image area has changed from the original G1 to a portion of G1 and a portion of G1+G2 to achieve a gray level interpolation and to enhance the gray control accuracy. Such configuration equivalents to increases the resolution of the image and regenerate a higher resolution image from the original image.

[0056] According to another example of the present invention, the image is shifted twice from the initial position A to position C then to position B in a width direction of the image, wherein a shifting distance between position A and position B is not greater than the width of one pixel of the image. As shown in FIG. 3, a, b, and d refer to predetermined areas in the image before shifting. b, d, and e refer the corresponding image areas after the first shift. d, e, and f refer the corresponding image areas after the second shift. Before shifting, the gray values of the image are: a:G1,b:G1,d:G1,e:G2,f:G3. After shifting twice, the gray values of the image are: a:G1, b:G1+G2, d:G1+G2+G3, e:G2+G3, f:G3. This example not only achieve the gray level interpolation but also enhance the gray level interpolation comparing to shifting the image once from point A to point B, so as to improve the gray control accuracy. Similarly, if the image are shifted multiple times from point A to point B, the result will be enhanced, so that the resolution of the final fusion image will be higher.

[0057] According to another example of the present invention, as shown in FIGS. 5 and 6, the image is shifted once from the initial position A to the first limited position B in a width direction of the image, wherein a shifting distance between position A and position B is half of a width of a pixel of the image. During shifting the image at the second time, the image is shifted from the first limited position B to a second limited position C in a height direction of the image, wherein a shifting distance between position B and position C is half of a height of the pixel of the image. During shifting the image at the third time, the image is shifted from the second limited position C to a third limited position D in the width direction of the image which is opposite direction of the first shift.

[0058] For macro analysis, a, b, d, and e in the figure refer to predetermined areas in the image before shifting, wherein the gray value is G1. b, c, e, and f refer to the corresponding images area after the first shift, wherein the gray value G2. e, f, h, and i refer to the corresponding images area after the second shift, wherein the gray value is G3. d, e, g, and h refer to the corresponding images area after the third shift, wherein the gray value is G4. After shifting the images three times with half pixel offset of the image, four images are fused, so that the gray values of the corresponding positions are superimposed to obtain the final fused image, as shown in FIG. 6. The gray levels before shifting the image are a:G1, b:G1, c:G2, d:G1, e:G1, f:G2, g:G4, h:G4, i:G3. The gray values after offset fusion are: a:G1, b:G1+G2, c:G2, d:G1+G4, e:G1+G2+G3+G4, f:G2+G3, g:G4, h:G4+G3, i:G3.

[0059] For micro analysis, it could also be understood that a, b, d, and e in FIG. 5 refer to a pixel in the image before the movement, wherein the gray value is G1. b, c, e, and f refer to the corresponding areas of the pixel after shifting half a pixel for the first time, wherein the gray value of this area is G2. e, f, h, i represent the corresponding area of the pixel after the second movement of half a pixel, and the gray value of this area is G3. d, e, g, h refer to the corresponding area of the pixel after the third shift, wherein the gray value of this area is G4. After shifting the images three times with half pixel offset of the image, four images are fused, so that the gray values of the corresponding positions are superimposed to obtain the final fused image, as shown in FIG. 6. The gray levels before the shift are a:G1, b:G1, c:G2, d:G1, e:G1, f:G2, g:G4, h:G4, i:G3. The gray values after offset fusion are: a:G1, b:G1+G2, c:G2, d:G1+G4, e:G1+G2+G3+G4, f:G2+G3, g:G4, h:G4+G3, i:G3. It can be determined that the gray value of the pixel corresponding to the original a, b, d, e has changed from the original single value G1 to a:G1, b:G1+G2, d:G1+G4, e:G1+G2+G3+G4. In other words, a whole original pixel abcd is divided into four new pixels a, b, d, and e, wherein each of new pixels has four different gray values so as to improve the resolution of the image.

[0060] As shown in FIGS. 5 and 6, it should be appreciated that whether the macro analysis or micro analysis for the image, without changing the resolution of the original image, more gray values are obtained after shifting the image and the gray control is more accurate that without shifting. By offsetting the width and height of the image by half a pixel, the resolution of the image is improved, so as to obtain a 3D print object with a smoother contour surface.

[0061] According to the preferred embodiment, multiple images are merged, or the pixel gray values of multiple images are superimposed, which is processed as follows.

[0062] According to the target light engine with resolution of 1920*1080, the size of each pixel is 100 um, the anti-aliasing level is selected as level 2, and the pixel offset is selected as the 2*2 mode. In other words, the offset corresponding to the embodiment shown in FIGS. 5 and 6. After forming four images from one original image through the shifting process, a corresponding area is calculated through anti-aliasing, so that each image will have its own gray scale. A grid map is then generated with the corresponding resolution, wherein the size is 1920*1080, wherein the number of grids is 1920*2*2 in the image width direction, and 1080*2*2 in the image height direction. For each line segment, when it intersects the grid graph, the pixels of the grid are illuminated. Then, a contour map is obtained with a width of 7680 and a height of 4320. By emitting rays to each line of the contour map, the contour can be filled with in and out information, to achieve the fusion of multiple images or the superposition of pixel gray values of multiple images so as to obtain a result image with a higher resolution.

[0063] In different examples, the images can be adjusted or processed according to different situations through specific superimposition or fusion process to obtain a smoother transition of the fused image.

[0064] FIG. 7 illustrates a gray scale situation corresponding to another example of the present invention. Through the above mentioned process to project an image for printing a single layer of a printed object, b is the superposition of gray levels from Tx0y0 to Txny0, d is the superposition of Tx0y0 to Tx0yn, e is the gray-scale superposition of Tx0y0 to Txnyn, f is the gray-scale superposition of Txny0 to Txnyn, and h is the gray-scale superposition of Tx0yn to Txnyn. Comparing the image without shifting, the overall grayscale control of the projected image is more accuracy by offsetting or shifting half a pixel. Especially the difference between adjacent gray scales at the edge is reduced, so the jagged condition around the image can be greatly reduced, and the contour surface of the printed object will be smoother.

[0065] In another example of the present invention, the image is shifted twice in the width and height directions. FIG. 8 illustrates a specific shifting process of the image. Assume that the width and height of one pixel of the image are set as 3 mm. The image is shifted in the X-axis direction each time, i.e. the width direction, wherein the shifting distance is ⅓ pixel, which is 1 mm. The image is shifted in the Y-axis direction each time, i.e. the height direction, wherein the shifting distance is ⅓ pixel, which is 1 mm. During the shifting process, the shift of coordinate values corresponding to the reference point (0,0) in the image as follows: Move from (0,0) to (1,0) to (2,0) to (2,1) to (1,1) to (0,1) to (0,2) to (1,2) to (2,2).

[0066] Similarly, under the conditions that the image is multiple shifted in the width and height directions and the total shifting distance in one direction is controlled not exceed one pixel, the more the image shifts, the smaller the dividing of the image in one single shifting, so as to enhance the accuracy of the gray scale control.

[0067] As shown in FIG. 9, the present invention provides an image processing method to improve an accuracy of a DLP 3D printing, which comprises the following steps.

[0068] Layer a 3D object to be printed to define a plurality of printing layers.

[0069] Operate a light engine. Project an original image on one of the printing layers, shift the original image slightly in width and height directions respectively via a specific shifting method, project another original image after each shift of the original image, overlay and fuse gray values of all the original images, and solidify the printing layer after the original images are fused for a predetermined period of time. Accordingly, the specific methods and processes of shifting the original images and fusing original images are the same as the working principles of the foregoing embodiment and examples.

[0070] Starting from the printing layer as the first layer to be printed, repeat the above steps to print each of the printing layers in sequence until all the printing layers are completed to form the 3D object.

[0071] When operating the DLP 3D printing, for each printing layer, the image shifting and gray scale fusion are performed similar to the foregoing embodiment and examples. The shifting operation can be performed by operating the light engine to move, operating the optical lens to move, or operating a printing platform to move, wherein the purpose of all of these operations is to shift the image to one position from its previous position. After each shift of the image, the image is project again to superimpose and fuse the gray values to solidify the resin material for a predetermined period of time so as to form the printing layer. Then, one of the light engine, the optical lens, and the printing platform is moved back to its original position, and then repeat the above operation for the next printing layer. Finally, the 3D object with smooth surface will be obtained.

[0072] The existing DLP printing method is that: turn on the light engine, project an image, solidify the layer for a predetermined period of time, turn off the light engine, and complete one of the printing layers. Then, project another image to form another printing layer by repeating the above steps. Through the conventional printing method, the change of the gray value of adjacent pixels in the projected image is too obvious at the contour of the object, such that the connecting surfaces of the object will be inconsistent and the surfaces of the object will be roughed after the object is printed.

[0073] The present invention provides a technical solution to improve the 3D printing result via an existing low resolution light engine through the above method without using a high resolution light engine. Therefore, the present invention improves the accuracy of DLP printing by reducing the grayscale difference between adjacent pixels of the image. Further, as the number of shifts increases, i.e. as the distance of each micro-displacement is smaller, the grayscale control is more precise and the grayscale difference between adjacent pixels at the contour of the printing object is smaller and smoother. So, the contour of the printing object will be smoother that the rippling mark on the contour of the printing object cannot be seen. Without changing the resolution of the light engine, the printing accuracy can be significantly improved by the present invention in form of software. The method of the present invention has advantages of low hardware cost, good printing effect, and high applicable value.

[0074] In addition, the method of the present invention can further be applied for color images. It is known that red, green, and blue are the primary colors of light. Firstly, if the original color of a predetermined point is RGB (R, G, B), the RGB color is converted to grayscale through a converting method. The grayscale of the color image is actually the pixel value after being converted into a black and white image. Then, the method of the present invention is applied to reduce the grayscale difference between adjacent pixels of the image and to increase the grayscale of the image. In other words, the more the gray levels, the clearer and more vivid the image level. Therefore, the method of the present invention is able to improve the resolution of the color image, and to enhance the clarity and realistic of the image.

[0075] While the embodiments and examples of the invention have been shown and described for the purposes of illustrating the functional and structural principles of the present invention, it will be apparent to one skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims.