JPS6238568A - Still picture recording system - Google Patents

Abstract

PURPOSE:To reduce the influence of the sensitivity difference between magnetic tapes by operating the difference between the preceding picture element level and the current picture element level of a still picture video signal and recording this difference. CONSTITUTION:The human eyes are insensitive to error in the change in a place where brightness is changed quickly. The gradation difference is approximated to the 31 kinds of level set as shown in a table, and the 16 kinds of level are selected from them in accordance with the gradation of the preceding picture element. For example, the level nearest to the gradation difference D of level is selected from the 16 kinds of level, 0-+63 in the table if the preceding picture element level is 0, and the level nearest to the gradation difference D of level is selected from the 16 kinds of level, -63-0 if the preceding picture element level is 63. That is, the still picture video signal which is subjected to A/D conversion and is stored in a memory is converted to an analog signal by a D/A converter, and the difference between the preceding picture element level and the current picture element level of the still picture video signal is operated and recorded. Thus, the influence of sensitivity difference between magnetic tapes is reduced.

Description

[Detailed Description of the Invention] Technical Field> The present invention converts a video signal brightness level signal of a still image that has been A/D converted and stored in a memory into an analog signal through a D/A converter, and converts this signal into an analog signal. This relates to a still image recording method that records directly onto magnetic tape.

<Prior Art> In the above-described still image recording method, if there is a sensitivity difference depending on the location (position) of the magnetic tape, the pixel level that should be the same will be reproduced at a different pixel level.

<Purpose> Accordingly, an object of the present invention is to provide a still image recording method that can reduce the influence of sensitivity differences between magnetic tapes.

<Embodiment> To explain the present invention in detail below, the still image recording method of the present invention calculates the difference between the previous pixel level and the current pixel level to reduce the number of recording gradations, instead of using the pixel level as it is at the time of recording.
This reduces the influence of sensitivity differences between magnetic tapes.

The present invention will be described in detail below using the recording format shown in FIG. 1, the microcomputer flowchart shown in FIG. 2, and Table 1.

Assume now that the brightness level of the still image stored in the memory is 6 bits. Since it is 6 bits, there are 64 gradations, and if this is D/A converted and recorded directly on a magnetic tape, if the sensitivity of the magnetic tape differs by 1/63, an error of 1 gradation will occur (the brightness level to be recorded is (at the age of 63). Therefore, the actual gradation of the reference pixel level is recorded accurately every n pixels (for example, n = 20) by dividing it into three times every 2 pixels, and the remaining (n-1) pixel levels are The 6 bits are compressed to 4 bits by the difference and recorded. With 4 bits, the gradation is 16, and an error will not occur unless the magnetic tape sensitivity differs by up to /15. Therefore, the influence of magnetic tape sensitivity can be reduced to 1/4.

That is, in FIG. 2, β is 1≦β≦(1)+1
), m is a variable with 1≦m≦n, and p is the total number of pixels, then p21. Top 2 in case of n+1.2n+1...
outputs the level of the bit, then outputs the level of the middle two bits, then outputs the level of the lower two bits, and the remaining (
n-1) pixel levels are the first pixel level and the (N-1) pixel level.
1.) Calculate the difference D (6 bits) from the pixel level, and select the gradation difference (4 bits) closest to this D from Table 1 and output. Repeat this process until e=p+1.

The above compression from 6 bits to 4 bits based on the difference in pixel levels (luminance levels) will be briefly explained. The human eye is sensitive to errors during changes in brightness in places where it changes slowly, but is insensitive to errors in changes in places where brightness changes rapidly. Therefore, the gradation difference is shown in Table 1.
Approximately 31 types are set as follows, and 16 types are selected from these according to the gradation of the previous pixel.

For example, if the previous pixel level is 0, 0 in Table 1
Select the level closest to the gradation difference between the levels from 16 types ranging from ~+63. Further, if the previous pixel level is 63, the level closest to the gradation difference in levels is selected from 16 types from -63 to 0 in Table 1.

It should be noted that the present invention is not limited to the above embodiments, and it goes without saying that many modifications and changes can be made to the above embodiments within the scope of the present invention.

<Effects> As is clear from the above description, the present invention converts a still image video signal that has been A/D converted and stored in a memory into an analog signal through a D/A converter, and converts this signal to a magnetic tape. The present invention relates to a still image recording method in which a difference between a previous pixel level and a current pixel level of a still image video signal is calculated, and this difference is recorded.

Therefore, according to the present invention, there is an excellent effect that the influence of the sensitivity difference between magnetic tapes can be reduced by using the difference.

[Brief explanation of the drawing]

FIG. 1 is a record 71 chart showing an embodiment of the present invention, and FIG. 2 is a 71 near chart of a microcomputer used in an embodiment of the present invention. Figure 1 Ani left, Figure 2 left

Claims (1)

[Claims] In a still image recording method, a still image video signal that has been A/D converted and stored in memory is converted to an analog signal through a D/A converter, and this signal is recorded on a magnetic tape.
A still image recording method characterized by calculating a difference between a previous pixel level and a current pixel level of a still image video signal and recording this difference.