第2803期:Your phone’s camera isn’t as good as you think(1)

When the Visualphone VP210 hit the market in 1999, it advertised a never-before-seen feature: a camera. With only 0.11 megapixels and storage for 20 photos, the Visualphone is a relic compared to modern devices sporting three distinct cameras, each with up to 100 times more resolution. But while this technology has improved dramatically in the 21st century, engineers are rapidly approaching a hard limit on phone camera quality.1999年，当Visualphone VP210上市时，它宣传了一项前所未有的功能——摄像头。这个摄像头仅有0.11百万像素，最多能储存20张照片。与当今配备三颗摄像头、分辨率高出上百倍的智能手机相比，Visualphone简直就是古董。然而，尽管这项技术在21世纪突飞猛进，工程师们如今正迅速接近手机相机质量的硬性极限。

To understand this limit, we first need to know how phone cameras work. Just like any other digital camera, when your phone takes a picture, light enters through its lens. This lens focuses the light onto an image sensor covered in a grid of photosites— microscopic light sensors roughly 100 times smaller than a grain of sand. There are millions of these sensors, and each one is covered by a red, green, or blue filter, allowing it to measure how much of that color is in the light hitting its location. Then these measurements are simplified, rounding them to less detailed numbers. This stepsacrificessome data, thus lowering the final images’ quality, but it’s essential for the camera’s processor. This computer can only handle so much information as it decrypts the three sets of color data to assemble a digital recreation of the image.要理解这个极限，我们首先得了解手机摄像头的工作原理。和其他数码相机一样，当手机拍照时，光线会通过镜头进入。镜头将光线聚焦到一个图像传感器上，这个传感器表面覆盖着由光敏单元（photosites）组成的网格——这些微型感光元件比一粒沙子小约100倍。这样的感光元件有上百万个，每一个上面都有红、绿或蓝的滤光片，使它能够测量到达该位置的光线中对应颜色的强度。接着，这些测量值会被简化，四舍五入成较粗略的数字。这一步虽然会牺牲部分数据，从而降低最终图像的质量，但却是摄像头处理器运作所必需的。因为这个微型计算机在解读三组颜色数据、重建数字图像的过程中，所能处理的信息量是有限的。

While the quality of this final photo depends on every part of the camera, nothing determines the look of a digital picture more than the image sensor. And engineers judge the quality of image sensors based on their performance in three areas. The first is resolution, or level of detail. Sensors with higher numbers of photosites offer better resolution, as the camera can collect more granular light data. Second and third are dynamic range and noise. Dynamic range is the span from light to dark within a single photo, and noise is the graininess that can come from poor lighting, long exposure times, or an overheating camera. Both these factors can be improved by using larger photosites, which can capture more light overall. This wider range of data helps processors better measure the intensity of the incoming light, adding contrast and reducing noise.虽然最终照片的质量取决于相机的每一个部分，但决定数码图像观感的关键因素，莫过于图像传感器。工程师通常从三个方面评估传感器的质量。第一是分辨率，即细节的清晰程度。拥有更多感光元件的传感器能提供更高的分辨率，因为它能收集更细微的光线数据。第二和第三是动态范围与噪点。动态范围指的是一张照片中从最亮到最暗的跨度，而噪点则是由于光线不足、曝光时间过长或摄像头过热而产生的颗粒感。这两者都可以通过使用更大的感光元件来改善，因为更大的感光面积能捕捉到更多光线。更宽的数据范围让处理器能更准确地判断光线强度，从而提升对比度并减少噪点。