JP4227859B2 - Mark sheet reader - Google Patents

Description

  The present invention relates to a mark sheet reading apparatus, and more particularly to a mark sheet reading apparatus that determines the presence or absence of a mark from the density of a mark entered on a mark sheet and outputs read data.

  As shown in FIG. 4, the conventional mark sheet reading apparatus of this type includes an image input unit 41, a density processing unit 42, and a mark determination unit 43. The image input unit 41 stores the actual form image in the multi-value memory. The multi-value memory contains a value corresponding to the density for each pixel. An example is shown in FIG. The density value has 10 levels from 0 to 9, and the closer to 0, the whiter, and the closer to 9, the black.

  The density processing unit 42 calculates the mark density value in the reading mark frame (enclosed by a rectangle) from the density value of each pixel input to the multilevel memory. For the calculation method, the maximum density value in the pixels surrounded by the mark frame is used as the mark density value, or each pixel density in the mark frame is added and the average value divided by the number of pixels in the mark frame is used. There is a method of setting the mark density value.

  The mark determination unit 43 compares the density value of the mark calculated by the density processing unit 42 with a predetermined density value (determination threshold value). If there is no mark. (For example, refer to Patent Document 1).

JP 7-146908 A

  In the above-described prior art, it may be difficult to distinguish a mark such as a single bar mark, a circle mark, a check mark, and noise (stained paper, unerased paper, etc.) (FIG. 5a). For example, when the density value of each pixel surrounded by the mark frame is as shown in FIGS. 5a to 5d, the mark density value of one bar mark (normal mark), paper stain, and unerased is calculated as shown in FIG. .

  When the maximum density value is the mark density value, if the threshold value is set to 8, the remaining unerased is determined to have no mark, but both the single bar mark and the paper surface stain are marked.

  When the average density value is the mark density value, if the determination threshold value is 2.0, it is determined that there is no mark on the paper surface, but it is determined that both the single bar mark and the unerased mark are present. That is, there is a problem in that any density calculation method cannot distinguish between a single bar mark to be read as a mark, a paper surface stain, and an unerased portion.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and the present invention distinguishes between a single bar mark, a check mark, etc., and a dirty or unerased form, thereby enabling stable mark reading. The purpose is to provide.

According to a first aspect of the present invention, in the mark sheet reading apparatus, an image input unit that inputs a plurality of mark images on the mark sheet, and multi-valued image data of the plurality of mark images read from the image input unit are stored. comprising: a multi-valued image memory, and a binary image memory for storing the binarized image data by binarizing with prespecified binarization threshold said multilevel image data, the multi-level image The maximum density value of the pixel for each mark of the data is compared with a preset threshold value, and the multivalued image data of the mark having the maximum density value equal to or higher than the set threshold value is used as the image data of the mark presence determination candidate Sorting, comparing the pixel size for each mark of the binarized image data corresponding to the image data of the mark determination candidate, with a preset size, and the setting Wherein the determining that there is the mark image data of the mark there determination candidate binarized image data having a size greater than size.

  Since the mark sheet reading apparatus of the present invention stably reads a single mark, a check mark, etc., the burden on the writer can be reduced as compared with the conventional mark filling.

Next, the best mode for carrying out the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a mark sheet reading apparatus according to an embodiment of the present invention.
An image input unit 1, a multi-value image memory 2, a binary image memory 3, and a CPU 4 are provided.

  A binary image obtained by binarizing the image data of the actual form from the image input unit 1 by the multi-level image memory 2 and the binarization threshold value specified in advance is stored in the binary image memory 3. The CPU 1 performs image processing on each image stored in the multi-value image memory 2 and the binary image memory 3 to determine the presence or absence of a mark, and outputs the read data to the outside.

FIG. 2 is a flowchart showing the operation of the present embodiment. As in the conventional technology Basically, an image is inputted (S1), it performs the concentration process (S2). If the density value is equal to or greater than a certain value (S3 YES), mark shape processing is performed (S4) and determination is performed (S5).

  FIG. 3 is an explanatory diagram for explaining the shape processing of the present embodiment. When the maximum value is the mark density value and the determination threshold value is 8 in b to d of FIG. 5, “single bar mark” and “stain on the paper surface” are objects of shape processing. At this time, if the binarized threshold value is 6, the binarized image will be as shown in FIGS.

  Next, the height (H) and width (W) of the binary image are obtained. As a result, “single bar mark” is W = 6 and H = 2, and “paper stain” is W = 3 and H = 2. A size to be read in advance as a mark is designated as height HT = 2 and width WT = 5.

  If the condition with a mark is W ≧ WT and H ≧ HT, only “one bar mark” has a mark.

It is a block diagram which shows the structure of embodiment of this invention. It is a flowchart figure which shows operation | movement of this embodiment. It is explanatory drawing explaining the shape process of this embodiment. It is a flowchart figure which shows the conventional mark reading procedure. It is explanatory drawing which shows the example of a mark entry, and its density distribution. It is explanatory drawing which shows the calculation state of a mark density value.

Explanation of symbols

1 Image Input Unit 2 Multilevel Image Memory 3 Binary Image Memory 4 CPU
5 External equipment

Claims (1)

In a mark sheet reader, an image input unit for inputting a plurality of mark images on the mark sheet, and the multi-level image memory for storing multi-value image data of the plurality of mark images read from the image input unit, the multi A binarized image memory that binarizes the binarized image data with a binarization threshold value specified in advance and stores the binarized image data, and the maximum number of pixels for each mark of the multilevel image data The density value is compared with a preset threshold value, multi-valued image data of a mark having a maximum density value equal to or higher than the set threshold value is selected as image data of the mark presence determination candidate, and the mark presence determination candidate Compare the pixel size for each mark of the binarized image data corresponding to the image data with a preset size, and have a size larger than the set size. Mark sheet reader, characterized in that determining that there is the mark image data binarized mark image data there judgment candidates that.

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