JPS6336382A - Picture processor - Google Patents

Abstract

PURPOSE:To improve an edge intensification and a contrast by executing a specified arithmetic operation and besides, changing, at least, an intensification coefficient and a correction coefficient K so as to correspond to the optical density of an original picture. CONSTITUTION:An original picture data is read out of a picture memory 5 by the aid of a CPU 1 and of a program memory 2, and sent to a computing element 7 and to a table memories 3 and 4. The table memory 3 refers to the intensification coefficients alpha and beta and the correction coefficient K corresponding to the optical density D0 at the position of the each picture element of the original picture data sent from the table memory 3, and the table memory 4 gives the optical density data for calculating the mask density DUS of the sent original picture data, to the computing element 7. According to this, the computing element 7, being calculating the mask density DUS, executes the arithmetic operation of an equation I for each picture element to constitute the original picture, obtains the optical density DP of the processed picture, and sends and displays it to/on a picture monitor 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an improvement in an image processing device that processes an image signal when it is transferred to and from an image memory.

[Background of the invention]

In recent years, many devices have come into use that read out images on X-ray photographic film or the like, convert them into electrical signals, and store the electrical signals in image memories. In such devices, when transmitting and receiving image signals to and from the image memory, it is necessary to obtain appropriate contrast and sharpness depending on the purpose of use of the reproduced image to be obtained, and in particular, to obtain good diagnostic performance for X-ray photographic film. Image processing is performed to make it appear.

As a conventional image processing method of this kind, Japanese Patent Application Laid-Open No. 55-8
There is one described in Japanese Patent No. 7953. In other words, when an original X-ray photograph is scanned, the X-ray image information recorded therein is read out, converted into an electrical signal, and then reproduced as a copy photograph, etc., the ultra-low space at each scanning point is used. Find the density Dus of the unsharp mask corresponding to the frequency, and calculate the density of the original photo. rg, the emphasis coefficient is β, and the density reproduced in a copy photo, etc. is D′, then 1)′= porg+β(Dorg ”us)
-...(1) is performed to emphasize frequency components of ultra-low spatial frequency or higher.

However, in such a conventional method, as can be seen from equation (1) above, the only coefficient used during calculation is the emphasis coefficient β. For this reason, the dynamic range of the image becomes narrower after frequency processing (edge enhancement processing), and when edge enhancement is performed, the overall contrast decreases, and there are problems in that it is not possible to improve both the two-edge enhancement and the contrast. Ta.

[Purpose of the invention]

The present invention has been made to solve the above-mentioned problems, and it is possible to give a wide dynamic range to the image after the two-edge enhancement process, and to improve both edge enhancement and contrast. The purpose is to provide an image processing device that can

[Summary of the invention]

The device of the present invention sets the density of the original image to Do, the mask density of the original image to Du3, α and β are emphasis coefficients, and K
When is the correction coefficient and the density of the processed image is DP, the following calculation is performed: D, = K (αD0 + βDus) (2), and at the same time, at least the emphasis coefficient β and the correction coefficient K are set to the original The above object is achieved by changing the density of the image.

[Embodiments of the invention]

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of an image processing device according to the present invention, in which 1 is a CPU that mainly controls each part of the device;
Reference numeral 2 denotes a memory (program memory) that stores a certain procedure (sequence) of device operation. Reference numeral 3 is a coefficient table memory in which the ratio of the emphasis coefficients α and β to the density D0 of the read original image (actually β since α is set to 1 here) and the correction coefficient K for the emphasis coefficient β are as follows. Reference numeral 24 is a mask density table memory, each of which is stored with an empirically or theoretically appropriate value, and stores density data to be used when calculating the mask density Du3 of the original image using equation (2) above. There is. Here, the mask density DulI of the original image refers to the density of each pixel position in the original image, which is set according to the pixel position rather than its actual density (usually centered around that pixel position). It refers to the concentration replaced by the average concentration within a certain area (mask). 5 is an image (original image) from an image reading device, external image recording device, etc. (not shown)
6 is an image after performing the calculation of equation (2) above on the original image (processed image)
This is an image memory that stores images. 7 is each memory 3.4
and an arithmetic unit that receives the data (α, K, Du3, and Do) from 5 and performs the calculation of equation (2) above; 8 is an image monitor that displays the original image and the processed image; 9 is an external path; 10 is an internal fast path.

FIG. 2 is a diagram showing an example of the density characteristics in the image processing process by the apparatus of the present invention.
+βD, 3iC (here, since α=1, D0+βDus, therefore, the calculated image data is almost the same as that in the conventional method expressed by equation (1) above). (c) is determined by the calculation of equation (2) above, but the density characteristic of the calculated image data when the correction coefficient iK is uniform (one pattern) regardless of the magnitude of the emphasis coefficient β; (d) shows the density characteristics of the calculated image data (processed image data) by the apparatus of the present invention.

Figure 3 shows the emphasis coefficient να (here α=
1, so Fig. 4 is a graph showing an example of a change in the enhancement coefficient β shown in Fig. 3 (in other words, in accordance with the density of the original image). It is a graph showing an example of change (correction function).

Next, the operation of the above-mentioned apparatus of the present invention will be explained with reference to these figures. By CPUI and program memory 2,
First, original image data is read from the image memory 5 and sent to the arithmetic unit 7 and table memories 3 and 4 via the internal high-speed path 10.

Thereby, the table memory 3 refers to the emphasis coefficient β and the correction coefficient K according to the density at each pixel position of the sent original image data, and the table memory 4 refers to the mask density Du3 of the sent original image data. Referring to the concentration data for calculation, each internal high-speed pass 10
It is given to the arithmetic unit 7 via. As a result, the calculator 7 calculates the mask density Du8 and performs the calculation of equation (2) above for each pixel constituting the original image, obtains a processed image, and sends it to the image monitor 8 for display as necessary. do.

In such arithmetic processing, if the original image data has the density characteristics shown in Figure 2 (,), then aD
The characteristic shown in FIG. 2(b) is obtained by the calculation o+βDus. This is multiplied by a correction coefficient K corresponding to the emphasis coefficient β, and the correspondence relationship between the emphasis coefficient β and the correction coefficient is shown in FIGS. 3 and 4. As can be seen from these figures, the correction coefficient is set so that the change (inclination) of the emphasis coefficient β is small in the region a where the change (inclination) is large, and changes greatly in the small region a. As a result, even in the gradation region where the emphasis coefficient β is constant, the correction coefficient K is different.
is given, and it is possible to perform frequency enhancement with contrast from a low density region to a high density region. FIG. 2(C) shows the characteristics when such a correction coefficient K is given and calculated.

(d). Here, in FIG. 2(C), a correction coefficient K is given at the time of calculation, regardless of whether it is small or large for the emphasis coefficient β.
This is a characteristic when it is uniform for the entire image (image data calculated by αD0+βI)us).

If the correction coefficient K is uniform in this manner, image data given a large emphasis coefficient β will not be overemphasized, and image data given a small emphasis coefficient β will be underemphasized.

In the present invention, the correspondence relationship between the emphasis coefficient β and the correction coefficient is
Instead of simply doing as shown in Figures 4 and 4, this correspondence relationship, that is, the correction coefficient K for the emphasis coefficient β, is changed according to the value of the emphasis coefficient β (dog, small), and the above formula (2) is used. Perform the calculation. As a result, the characteristics shown in FIG. 2(d) are obtained, with a wide dynamic lens, just the right two-horn emphasis, and a suitable contrast.

Note that the settings for the correction coefficients are not limited to those shown in FIG. 4, and may be set as shown in FIGS. 5 and 6, for example. In other words, this correction coefficient includes the type of image and the selection of the part of interest in the image, in other words, the density of the image to be observed (the emphasis coefficient β set according to this density)
Various settings can be made depending on the situation.

〔Effect of the invention〕

As described above, according to the present invention, in the ethos enhancement process, a wide dynamic lens can be given to the processed image, and both the ethos enhancement and the contrast can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the device of the present invention, and FIG.
The figure is a density characteristic diagram for explaining the arithmetic operation of the device, Figures 3 and 4 are graphs showing examples of the correspondence between emphasis coefficients and correction coefficients, and Figures 5 and 6 are correction coefficient settings. It is a graph showing another example of. ■...CPU, 3...Coefficient table memory, 4...
- Table memory for mask density, 5... Image memory for original image, 6... Image memory for processed image, 7
...Arithmetic unit.

Claims (1)

[Claims] 1. The density of the original image is D_o, the mask density of the original image is D_u_s, α and β are emphasis coefficients, and K
is a correction coefficient, and when the density of the processed image is D_P, D_P=K(αD_o+βD_u_s), and when the calculation means performs the calculation, the emphasis is adjusted according to the density D_o of the original image. An image processing device comprising: coefficient variable means for respectively varying a coefficient β and a correction coefficient K.