图象增强显示通常采用两种方式:一是陡式线性增强。把输出亮度信号和输入温度信号的比值,从正常情况下等于1变成大于1,从而提高了某一温度范围的放大比例,扩展了灰度级别。二是阶梯函数增强。把几个特定的温度范围和几个特定的灰级对应起来,提高了灰度等级的对比度。这种方式运用在云顶较高、温度较低的区域效果较好。实际工作中,往往把这两种方式结合起来应用。 近几年来,国内一些单位在研制增强处理设备工作中,取得了一些可喜的成果,对改进预报工作起到了一定作用。我们在试制低分辨率红外云图增措显示电路时,采用了集成元件,从而简化了电路设计。井实现了结构小型化,整个电路装在200×100mm的印刷电路板上,可插接在118传真机中。 该电路兼有阶梯函数增强和陡式线性增强两种功能,处理分界点的亮度温度选择在一25.7℃ 即灰度标尺的第8级。阶梯变化也采用四级,每一级的温度范围相当灰度标尺的两级温度。 增强电路主要由三部分组成:电压比较器、模拟电子开关兼放大电路和加法器。电原理见附图。 Image enhancement display is usually used in two ways: First, steep linear enhancement. The ratio of the output luminance signal to the input temperature signal is changed from 1 to greater than 1 under normal conditions, thereby increasing the amplification ratio of a certain temperature range and extending the gray level. The second is the ladder function enhancement. Corresponding to several specific temperature ranges and several specific gray levels increases the gray level contrast. This method is used in the cloud top, the lower the temperature is better. In actual work, these two methods are often used in combination. In recent years, some units in China have made some gratifying achievements in the development of enhanced processing equipment and played a certain role in improving the forecasting work. When we prototyped a low-resolution infrared cloud zoom display circuit, we used integrated components to simplify the circuit design. The well achieved the miniaturization of the structure, the entire circuit mounted on a 200 × 100mm printed circuit board, can be plugged in the 118 fax machine. This circuit has both functions of step function enhancement and steep linear enhancement, and the brightness temperature of the demarcation point is selected at a level of 25.7 ° C which is the grayscale scale. Step changes are also used four levels, each level of temperature range of two grayscale scale temperature. Enhancement circuit is mainly composed of three parts: voltage comparator, analog electronic switch and amplifier and adder. See the photo of the principle of electricity.