Why Smartphone Photo Preview Quality Matters

Before pressing the shutter to take a picture, a photographer has an idea of how the final capture will look based on what is shown on the camera’s preview screen. A smartphone?#photographer?needs to keep in mind that?#smartphones?do not use the same processing pipeline for preview and the actual capture because they must optimize the energy consumption of the app and are limited with the software power. Hence, they cannot implement the same image-processing refinements on each frame during the preview that they do for the actual image.

Most phones today aim at rendering an effective 30 fps during preview. This proves to be a tough challenge for low-light photography. In this context, many smartphones will reduce the number of frames per second to provide longer exposure time. This comes at the price of reducing the fluidity of the screen, which diminishes the #userexperience. But this is not all: In very low-light conditions, the low frame rate still does not allow for very long exposure time, which can lead to an overly dark preview of the scene.

Let’s take the example of the? 三星电子 ?Galaxy?#S23Ultra. At 1 lux, the S23 Ultra provides slightly more than 11 frames per second, which limits the exposure time of each frame to 1/11=89ms. Yet, when taking the picture, it achieves an exposure time of 250ms based on the exif of the captured image. The preview image is then captured with lower exposure time leading to lower signal to noise ratio. The final picture (the second image) is much brighter and more pleasant than what the preview seemed to promise. Would you have taken this photo?