509:. A region boundary is approximated with several curve segments. To keep a curve smooth, the joints of two curves are constrained so the tangents match. One problem is determining where a curve bends so sharply that it should not be smooth. The smooth portions of a curve are then approximated with a Bézier curve fitting procedure. Successive division may be used. Such a fitting procedure tries to fit the curve with a single cubic curve; if the fit is acceptable, then the procedure stops. Otherwise, it selects some advantageous point along the curve and breaks the curve into two parts. It then fits the parts while keeping the joint tangent. If the fit is still unacceptable, then it breaks the curve into more parts.
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quantization/posterization; some brush spots disappeared. Some letters survived the vectorization with distortion, but most letters were discarded. Losing the letters is not a big issue; post conversion editing would want to delete the annotation and replace it with text rather than curves. Thin lines crossing at a shallow angle made filled regions, and intersecting outlines of filled regions became confused; see lower right corner. The tracing also has some odd features. Many black outlines touch, so they become large, complicated, objects rather than just outlines for specific regions. Instead of just a background, a rectangular white region separates the two outlined rectangles. The objects labeled
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curved lines, and there may be several line weights (thick for objects and thin for dimension lines). Instead of (or in addition to) curves, the image may contain outlines filled with the same color. Adobe
Streamline allows users to select a combination of line recognition (horizontal and vertical lines), centerline recognition, or outline recognition. Streamline also allows small outline shapes to be thrown out; the notion is such small shapes are noise. The user may set the noise level between 0 and 1000; an outline that has fewer pixels than that setting is discarded.
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the computer, Pepper states: "Those proficient with a graphic tablet and stylus could make the following changes directly in CorelDRAW by using a scan of the sketch as an underlay and drawing over it. I prefer to use pen and ink, and a light table"; most of the final image was traced by hand in ink. Later the line-drawing image was scanned at 600 dpi, cleaned up in a paint program, and then automatically traced with a program. Once the black and white image was in the graphics program, some other elements were added and the figure was colored.
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404:. Some of these programs have a command line interface while others are interactive that allow the user to adjust the conversion settings and view the result. Adobe Streamline is not only an interactive program, but it also allows a user to manually edit the input bitmap and the output curves. Corel's PowerTRACE is accessed through CorelDRAW; CorelDRAW can be used to modify the input bitmap and edit the output curves. Adobe Illustrator has a facility to trace individual curves.
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pixelation problems that a bitmap has when it is magnified. Instead, the vectorization program needs to approximate the region boundary with lines and curves that closely follow the pixel boundaries but are not exactly the pixel boundaries. A tolerance parameter tells the program how closely it should follow the pixel boundaries.
380:). Then a person can manually trace the elements of the image using the program's editing features. Curves in the original image can be approximated with lines, arcs, and Bézier curves. An illustration program allows spline knots to be adjusted for a close fit. Manual vectorization is possible, but it can be tedious.
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The image can be vectorized manually. A person could look at the image, make some measurements, and then write the output file by hand. That was the case for the vectorization of a technical illustration about neutrinos. The illustration has a few geometric shapes and a lot of text; it was relatively
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Some vectorizers are standalone programs, but many have interactive interfaces that allow a user to adjust the program parameters and quickly see the result. PowerTRACE, for example, can display the original image and preview the converted image so the user may compare them; the program also reports
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Reducing the number of colors in an image is often aided by a histogram. The most common colors may be selected as the representatives, and other colors are mapped to their closest representative. When the number of colors is set to two, the user may be asked to make threshold and contrast settings.
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Many of the vectorization programs will group same-color pixels into lines, curves, or outlined shapes. If each possible color is grouped into its object, there can be an enormous number of objects. Instead, the user is asked to select a finite number of colors (usually less than 256), the image is
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Although graphics drawing programs have been around for a long time, artists may find the freehand drawing facilities awkward even when a drawing tablet is used. Instead of using a program, Pepper recommends making an initial sketch on paper. Instead of scanning the sketch and tracing it freehand in
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Another issue is the number of colors in the image. Even images that were created as black on white drawings may end up with many shades of gray. Some line-drawing routines employ anti-aliasing; a pixel completely covered by the line will be black, but a pixel that is only partially covered will be
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Vectorization is also used to recover information that was originally in a vector format but has been lost or has become unavailable. A company may have commissioned a logo from a graphic arts firm. Although the graphics firm used a vector format, the client company may not have received a copy of
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One issue is what the predominant shapes are. If the image is of a fill-in form, then it will probably have just vertical and horizontal lines of a constant width. The program's vectorization should take that into account. On the other hand, a CAD drawing may have lines at any angle, there may be
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Similarly, Ploch recreated a design from a digital photograph. The JPEG was imported and some "basic shapes" were traced by hand and colored in the graphics drawing program; more complex shapes were handled differently. Ploch used a bitmap editor to remove the background and crop the more complex
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Vectorization can be used to update images or recover work. Personal computers often come with a simple paint program that produces a bitmap output file. These programs allow users to make simple illustrations by adding text, drawing outlines, and filling outlines with a specific color. Only the
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in mollusks. The upper portion is mostly a one-pen-width filled outline diagram, but it has a mesh gradient fill along the bottom of the shell and along the bottom of the food. It also has some artistic brushes on the upper left of the shell. The bottom portion of the illustration has four line
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The 531×879 pixel image was traced; 50 colors were used. Most (if not all) lines were lost; they were turned into black regions, and their effective line widths varied. The black outline around the blue food in the upper part disappeared. The gradient fills and brushed spots were lost to color
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Vectorization is usually inappropriate for continuous tone images such as portraits. The result is often poor. For example, many different image tracing algorithms were applied to a 25 kB JPEG image. The resulting vector images are at least a factor of ten larger and may have pronounced
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The vectorization program will want to group a region of the same color into a single object. It can do that by making the region boundary exactly follow the pixel boundaries, but the result will be a boundary of often short orthogonal lines. The resulting conversion will also have the same
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This image illustrates the difference between bitmap and vector images. The bitmap image is composed of a fixed set of pixels, while the vector image is composed of a fixed set of shapes. In the picture, scaling the bitmap reveals the pixels while scaling the vector image preserves the
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Automated programs can have mixed results. A program (PowerTRACE) was used to convert a PNG map to SVG. The program did a good job on the map boundaries (the most tedious task in the tracing) and the settings dropped out all the text (small objects). The text was manually re-inserted.
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The task in vectorization is to convert a two-dimensional image into a two-dimensional vector representation of the image. It is not examining the image and attempting to recognize or extract a three-dimensional model that may be depicted; i.e. it is not a
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The original image did not have any curves (except for the text), so the conversion is straightforward. Curves make the conversion more complicated. Manual vectorization of complicated shapes can be facilitated by the tracing function built into some
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Synthetic images such as maps, cartoons, logos, clip art, and technical drawings are suitable for vectorization. Those images could have been originally made as vector images because they are based on geometric shapes or drawn with simple curves.
217:. While such an image is useful, it has some limits. If the image is magnified enough, its artifacts appear. The halftone dots, film grains, and pixels become apparent. Images of sharp edges become fuzzy or jagged. See, for example,
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with a fountain pen, a 0.7 mm gel pen, and a 0.5 mm HB pencil. The images were scanned at 600 pixels per inch with 24-bit RGB. The line widths end up being 10 to 14 pixels wide. The ink colors are not uniform and have
221:. Ideally, a vector image does not have the same problem. Edges and filled areas are represented as mathematical curves or gradients, and they can be magnified arbitrarily (though of course the final image must also be
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gray. If the original image is on paper and is scanned, there is a similar result: edge pixels will be gray. Sometimes images are compressed (e.g., JPEG images), and the compression will introduce gray levels.
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results of these operations (the pixels) are saved in the resulting bitmap; the drawing and filling operations are discarded. Vectorization can be used to recapture some of the information that was lost.
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There are many different image styles and possibilities, and no single vectorization method works well on all images. Consequently, vectorization programs have many options that influence the result.
237:; characters are treated as lines, curves, or filled objects without attaching any significance to them. In vectorization, the shape of the character is preserved, so artistic embellishments remain.
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image components. He then printed the image and traced it by hand onto tracing paper to get a clean black and white line drawing. That drawing was scanned and then vectorized with a program.
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A contrast setting looks for significant changes in pixel color rather than a particular color; consequently, it may ignore the gradual color variations in a
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that put light pixels within the lines. The pencil lines also have interior defects due to the roughness (tooth) of the paper. The scan also has some
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Scanned images often have a lot of noise. The bitmap image may need a lot of work to clean it up. Erase stray marks and fill in lines and areas.
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The input to vectorization is an image, but an image may come in many forms such as a photograph, a drawing on paper, or one of several
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Other conversions may not go as well. The results depend on having high-quality scans, reasonable settings, and good algorithms.
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easy to convert the shapes, and the SVG vector format allows the text (even subscripts and superscripts) to be entered easily.
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Traced with PowerTRACE using detailed logo, smoothing 40, detail +2.5; result: 50 colors, 94 curves, 2452 nodes, 96 kB.
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Schneider, Philip J. (1990), "An
Algorithm for Automatically Fitting Digitized Curves", in Glassner, Andrew S. (ed.),
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that format. The company may then acquire a vector format by scanning and vectorizing a paper copy of the logo.
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in to be rendered, and its quality depends on the quality of the rasterization algorithm for the given inputs).
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An image does not have any structure: it is just a collection of marks on paper, grains in film, or pixels in a
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weights and some small characters; the color fill is simple except for a gradient at the jagged lines.
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Continuous tone photographs (such as live portraits) are not good candidates for vectorization.
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Itoh, Koichi; Ohno, Yoshio (September 1993), "A curve fitting algorithm for character fonts",
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Map after automated conversion and touch up to re-add the labels and adjust colors (18 kB)
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Although these lines may look solid, they are far from perfect. The lines were drawn on
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Please help update this article to reflect recent events or newly available information.
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Vectorization is effective on single colored, nongradient input data, like signatures.
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The end result of many vectorization programs are curves consisting of cubic
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etc.) are scanned, vectorized, and written as CAD files in a process called
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Vectorized two-color (black & white) variant of the signature of
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1055:(version 3 for Windows ed.), Mountain View, CA: Adobe Systems
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posterization effects when a small number of colors are used.
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are not simple layered shapes; the desired result would have
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On the right is an illustration showing the operation of the
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Corel advice: Put the image on a light table, cover it with
627:, graphics can be vectorized for easier usage and resizing.
612:(GIS) satellite or aerial images are vectorized to create
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Vectorization is the inverse operation corresponding to
1128:"Sub-pixel Edge Detection in Character Digitization"
843:Comparison of raster-to-vector conversion software
27:Conversion of raster graphics into vector graphics
1100:, Boston, MA: Academic Press, pp. 612–626,
482:reduced to using that many colors (this step is
1134:, Cambridge University Press, pp. 54–64,
1089:CorelDRAW Handbook: Insights from the Experts
1080:CorelDRAW Handbook: Insights from the Experts
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64:Learn how and when to remove these messages
513:information such as the number of curves.
490:. Gradient fills will also be posterized.
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630:Vectorization is often the first step in
160:Learn how and when to remove this message
1177:Taking Corel PowerTRACE for a Test Drive
1132:Raster Imaging and Digital Typography II
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400:(discontinued), Corel's PowerTRACE, and
137:of all important aspects of the article.
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530:Original artwork in PNG format; 115 kB.
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133:Please consider expanding the lead to
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135:provide an accessible overview
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878:Optical character recognition
337:Hand converted to SVG (47 kB)
235:optical character recognition
1062:Adobe Illustrator User Guide
289:. Common vector formats are
1053:Adobe Streamline User Guide
182:raster-to-vector conversion
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1156:(3), John Wiley: 195–205,
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329:Original PNG file (16 kB)
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1018:Itoh & Ohno 1993
853:Discretization error
679:Christopher Columbus
656:Christopher Columbus
460:specular reflections
186:raster vectorization
268:raster file formats
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122:lead section
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47:Please help
44:
978:Adobe (1998
906:Pepper 2005
804:Vectormagic
789:Vectormagic
625:photography
246:integration
1071:User Guide
1040:Corel 2005
1006:Adobe 1992
994:Adobe 1992
966:Adobe 1992
954:Adobe 1992
942:Adobe 1992
930:Adobe 1998
918:Ploch 2005
894:References
848:Digitizing
636:signatures
595:blueprints
466:artifacts.
223:rasterized
219:pixelation
200:Background
143:April 2023
50:improve it
1158:CiteSeerX
888:Subpaving
738:AutoTrace
392:Automatic
374:CorelDRAW
368:(such as
256:methods.
254:heuristic
127:summarize
56:talk page
18:Autotrace
1186:Category
827:See also
774:Scan2CAD
754:Inkscape
722:RaveGrid
378:Inkscape
96:May 2023
758:potrace
517:Example
445:Options
402:Potrace
321:Process
209:shapes.
86:updated
1160:
1138:
1104:
564:, and
549:radula
455:vellum
435:vellum
345:Manual
248:is to
215:bitmap
376:, or
244:, as
192:into
1136:ISBN
1102:ISBN
706:JPEG
660:JPEG
623:and
614:maps
305:and
278:and
272:TIFF
658:as
632:OCR
619:In
608:In
601:or
589:In
303:EMF
299:EPS
295:DXF
291:SVG
280:PNG
276:BMP
184:or
172:In
1188::
1152:,
664:kB
580:.
578:op
574:rp
570:rr
566:rr
562:rp
560:,
558:op
372:,
358:.
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307:AI
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