测试卡展示

测试卡说明

多段灰度测试图 爱莎测试卡16:9 反射型T07A 透射型T07D可定制

测试图被设计用于电子照相机的调制深度的半色调再现和频率响应评估。

在灰色背景（D= 0.75，remission=18％）的中心位置被布置一行光栅，其产生的摄像机输出信息0.5到10MHz的频率。上下两条逆流的黑白灰度测试条分布。

其校准的灰块从1到11的密度和反射率值如下表：

这里说密度是基于BASO4=0和等级等于0.15级别。两个外区域（0和12）是白色的（D =0.05，反射率= 90％）和黑色。由于反射材料的在本领域应用的可能性可以设计出比等级11（D??1.55）密度***的测试卡。

灰阶实现半色调再现的评估。具有特殊的测量系统（VX700，视频选项，Optest VTC1），也可以决定照相机的伽马。

使用线栅格能够确定对比度变换函数。脉冲串信号幅度参考值是在0.5MHz。为了可以测量中间、上下边缘的CTF（对比度传递函数）摄像机必须上下回转。必须小心避免信号消减影响黑白级别测定。

测量程序

测量可以在各种相机输出信号进行，但优选在Y亮度信号（或编码Y中***B和W平衡）。在图像的中心和角测量，记录拍摄镜头的横向色相差。除了确定相机响应的特定值5MHz，根据其他频率的响应的测量值来绘制一个曲线，根据测试卡分析的空间频率给出对比度损失（或调制）。推荐测量0.5兆赫和1至7兆赫的频率脉冲串。测量得到CTF。

计算公式可以根据CTF值来计算MTF：

MTF（8N）=π/4 CTF（N）+1/3 CTF（3N） - 1/5 CTF（5N）+1/7 CTF（7N） - 1/9 CTF（9N）+1/11 CTF （11N）...]

其中，N是所分析的测试卡的空间频率; N=TVL/ H

English Description

The test chart is designed for evaluation of the halftone reproduction and frequency response of the modulation depth of electronic cameras.

In the center of a gray background (D=0.75, remission=18%) a line raster is arranged which generates frequencies of 0.5 to 10 MHz in the output signal of the camera. Above and below these black and white lines counter current gray scales are arranged. Their calibrated gray fields 1 to 11 show the following densities and reflectance values:

The density are based on a density of BASO4 = 0 and graduated in equal steps of 0.15. The two outer fields (0 and 12) are white (D=0.05, reflectance=90%) and black. Due to the possibilities of reflective material this field has a lower density than the step 11 ( D ~ 1.55).

The gray scales allow the assessment of half tone reproduction. With special measuring systems (VM 700, video option, Optest VTC 1) it is also possible to determine the gamma of the camera.

With the line rasters it is possible to determine the contrast transformation function. The reference value is the signal amplitude of the 0.5 MHz burst. To measure the CTF (contrast transfer function) not only in the middle but also on the upper and lower edges the camera has to be swiveled downwards and upwards. Care must be taken to avoid clipping of the signal to be measured at the black and white level.

Measurement procedures

Measurement can be made on the various camera output signals, but preferably on the Y luminance signal (or coded Y with perfect B and W balance). The measurement is made at the center of the image and the corners so that the account is taken of the lateral chromatic aberration of the lens. In addition to determining camera response to the particular value of 5 MHz, measurement of the response at the other frequencies serves to plot a curve giving contrast loss ( or modulation) according to the spatial frequency of the test chart analyzed. Frequency bursts of 0.5 MHz and 1 to 7 MHz are recommended for this measurement. The measurements give the CTF.

Mathematical relations can be used to calculate the MTF according to the CTF values:

MTF(8N)= π /4 [CTF(N) + 1/3 CTF(3N) - 1/5 CTF(5N) + 1/7 CTF( 7N) - 1/9 CTF(9N) + 1/11 CTF(11N)...]

where N is the spatial frequency of the test chart analyzed; N in TVL/ H

购