JPS6340462A - Picture quality controller - Google Patents

Abstract

PURPOSE:To partially intensify a picture by detecting the density of a designated first region, and correcting the density of a second region designated independently of the first region based on the detected density. CONSTITUTION:A WP and a BP show respectively the maximum white level and the maximum black level in a previously determined main scanning interval. For instance, in the case of an original composed of four regions (I)-(IV), at first an operator inputs previously these four regions in a device. Here, the examples of the histograms of the WP and the BP in character regions (I) and (II), are shown in figures (b) and (d). The region (I) is the rather weak character region and the region (II) is of a rather high density at its ground surface. In such a case, if conversion tables, the shapes which are shown respectively in figures (c) and (d), are selected corresponding to the regions (I) and (II) respectively, the character part is outputted while being intensified at ground surface parts, for each of the regions (I) and (II).

Description

[Detailed description of the invention] (Field to which the invention belongs) The present invention relates to an image quality control device for multi-gradation images.

(Prior Art) Devices for reading, processing, and outputting multi-tone images have been devised in the past.

Generally, in the case of multi-tone image data, the density of a part of the read image may have an important meaning. In such a case, there arises a demand for outputting an image with emphasis on an image of an important region. Conventionally, it has been desired to realize a device that fully satisfies such requirements.

〔the purpose〕

In view of the above points, the present invention pays attention to the density of a region specified by the operator in a multi-tone original, and performs density conversion to emphasize and output the image of that part. This is for image enhancement.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 2(a) and 2(b) are a side view and a plan view, respectively, of the image reading device in this embodiment.

1 is the document to be read, 2 is the transparent document table, 3-1.3-2
Reference numerals denote lamps 4-1, 4-2, and 4-3 for illuminating the original, 4-3 a mirror, 5 a lens, and 6 a CCD.

The image of the original 1 illuminated by the lamp 3-1.3-2 is captured by the mirror 4-1.4-2.4-3. An image is formed on the CCDa through the lens 5.

2. At the same time as performing electric scanning (hereinafter referred to as main scanning, X in the figure) on the CCD, the lamp 3-1°3-2. The mirror 4-1.4-2.4-3 mechanically performs scanning (hereinafter referred to as sub-scanning, Y in the figure) to scan the original.

FIG. 3 shows the image reading procedure in this embodiment.

First, step 18 is a 117r scan, in which two scans are performed once before the main scan for outputting an image, and feature parameters of the document are captured.

Step 19 creates a density conversion table using the feature parameters taken in step 18.

Next, in accordance with the density conversion table created in step 19, main scanning is performed in step 20, and an image is output at the same time as the document is read.

FIG. 4 describes the document characteristic parameters used in this embodiment. If there is a manuscript like Figure 2 (a) 1,
The output after A/D conversion and the characteristic parameters when white is O1 and black is 255 for one main scanning line will be shown.

AV is a predetermined main scanning position AP, and AP-
WP and BP are the density average values at 8 points from 3 to AP+4, respectively, and WP and BP are respectively determined in the predetermined main scanning section [PS
, maximum white level in PF3.

Indicates maximum black level.

That is, main scanning position i (=0.1, 2°3, --
----) is the output after A/D conversion of the CCD d(
i), the following equation holds.

In this embodiment, AV is used to know the gradation information of a document, and AP may be specified for a portion where gradation information is considered important, such as a photographic document.

In addition, WP and BP are used to find out the maximum black level and maximum white level of a document, and SP and BP are used in areas where the density information of text and background areas is considered important, such as text manuscripts.
If you specify EP.

Furthermore, main scanning - WP detected for each line.

The values of BP and 'AV are counted, as shown in FIG. 5(a).

As shown in (b) and (c), the histogram is shaped and used to calculate the density conversion table.

FIG. 1 is a block diagram showing the electrical configuration of this embodiment.

6 is the above-mentioned CCD, 7 is an inverting amplifier (hereinafter referred to as amplifier), 8
is an A/D converter (hereinafter referred to as A, D, and C), and 9 is R for concentration conversion.
AM (hereinafter referred to as conversion RAM), 10 is a white peak/black peak detector (hereinafter referred to as wp/BP detector), 11 is an interval average value detector (hereinafter referred to as AV detector), 12 is MPU, +3.14.
15 is a selector, and 16 is an output side interface 17, which is a latch.

The image signal read by the CCD 6 is inverted and amplified by the amplifier 7, and then quantized to 8 bits by A, D, and C8.
It is sent to the selector 13.

First, in the pre-scan, the MPU 12 instructs the WP/BP detector in the peak detection sections PS and P according to the operator's instructions.
E is specified, and the average value detection point AP is specified in the AV detector 11. Furthermore, by switching the selector 13 to the lower side in the figure, the data from A, D, and C8 are sent to the WP/BP detector 11, and the values of the feature parameters WP, BP, and AV are determined for each main scanning line. It is calculated and sent to the MPU 12.

The MPU 12 receives the sent feature parameters WP, BP,
The AV value is counted only in the necessary sub-scanning section, and the histogram shown in FIG. 5 is created. Also, depending on the case,
The values of PS, PE, and AP are switched during sub-scanning to create a histogram of the characteristic parameters of a non-rectangular area or multiple areas.

After the main scan is completed, the selectors 14 and 15 are switched to the lower side, and the conversion RAM 9 is switched to the MPU 12 side. Furthermore, a density conversion table is created using the obtained Hiss I/Durum values of WP, BP, and AV, and is written into the RAM 9.

Conversion RAM 9 stores data before density conversion at lower address 8.
Data 8 after density conversion for bit (AoNA7)
Bits (Do-D7) are written correspondingly, but the 3 bits of the second address (Aa'-Ago) are changed by the MPU 12 via the latch 17, so a maximum of 8 types of conversion tables can be written for one data. It is possible to switch between

After the density conversion table is written to the conversion RAM, the MP
The U 12 moves to the main scanning operation after switching all the selectors 13, 14, and 15 to the upper side.

During the main scan, the MPU 12 selects one of the eight types of density conversion tables written in the conversion RAM 9, and reads the table while switching to the one that is considered the most appropriate.

Figure 6 shows specific WP, BP, and
The shape of an AV histogram and the shape of a density conversion table that is considered appropriate for emphasizing each area are shown.

For example, in a document consisting of four areas as shown in FIG. 6(a), the operator first inputs these four areas into the apparatus in advance. Therefore, character area (I) (11
) Histogram examples of WP and BP in (b) and (d
). (I) is a relatively domain-based domain, and (II) is a domain with a relatively high background concentration. This and crucian carp, (I)
(11) Create a temperature conversion table corresponding to each region (
c) If we choose a shape like (e), (1) (
For each of the areas 11), it is possible to output the character part with emphasis on the background part ''.

Furthermore, examples of AV histograms in the photographic area (Ill) (IV) are shown in (f) and (h). (Ill
) is. At this time, for the areas (Ill) and (IV), the density conversion tables are respectively set as (g) and (i).
), it is possible to perform image enhancement that gives many gradations to densities that occur frequently.

These four types of density conversion tables (c), (e), (g), and (i) are written into the conversion RAM 9 and sent to the MPU 12.
Each table is successively displayed by switching A8 to AIG.

During main scanning, A8 to AIO in RAM 9 are stored during main scanning and sub-scanning in order to perform density correction within the corresponding areas.
Switch.

For example, four areas (I), (11), (affected II).

(c), (e), and (g) for (IV), respectively.

By performing density correction using the density conversion table shown in (i), it is possible to output an image that is emphasized in each area. In addition, if there is particularly important information in the text area (I) and photo area (IV) and you want to emphasize these areas, use the text areas (I) and (11).
In the part shown in (e), the density is corrected using the density conversion table shown in (e), and the photographic area (Ill) and (IV
), density correction is performed using the density conversion table shown in (f).

(Effects) As described above, in the present invention, appropriate density correction output can be performed even for originals containing mixed text, photographs, etc., or originals consisting of parts with completely different density distributions, such as a composite original. Can be done.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the electrical configuration Fig. 2 is a side view and plan view of this embodiment Fig. 3 is a diagram showing the procedure for image reading Fig. 4 is an image signal and each characteristic in one main scanning line FIG. 5 is a diagram showing parameters; FIG. 5 is a diagram showing an example of a histogram for each feature parameter; FIG. 6 is a diagram showing a relationship between an image area and a histogram density conversion table.

Claims (1)

[Claims] An image quality control device that detects the density of a specified first area and performs density correction on a specified second area independently of the first area based on the detected density. .