问题
I need to know that different between scanning and taking photo from camera . As example we normally , SCAN QR code , bar code , like thing using android phone.They are also image. we can take photo from camera. it also image.
So ,is it Scanning QR code , mean take image and processing it or are there have any special thing take image from pixel values ?
回答1:
Biggest difference is that when you capture an image you get a processed jpg file, when you're scanning you're working with raw YUV byte array.
When talking about a picture you usually need to worry about quality, flash, aperture, shutter speed, iso, white balance and a lot of other things that will make it a good picture and nice for people to see, and when you're working with a scan you usually don't care much about any of these things, you just need to get information from the image.
Another big difference is that you can capture a lot of YUV bytes very fast, while taking a picture takes time.
That covers the basic differences, but there's a lot of info when talking about photo and scanning, and more when you enter a specific subject. I suggest you to read about Camera and Camera preview.
回答2:
The similarity between scanning and capturing is that data stored is in the form of image. However, there is a difference in quality of both the images. While capturing image from camera, you can vary the focus in order to get sharp image of 3D object. Beside that there are exposure controls within the camera which helps in this process. Scanning produces image taking line by line information. It works well for flat objects like papers and documents kept at very close distance. So, in your example of barcode, scanning and capturing image will use similar process but produce two different results in terms of quality.
回答3:
In order to get the value of an QR-Code in the real world, you need to first capture an image containing the QR-Code.
Once you have this image, you can scan it for the QR-Code and do some processing in order to decode it.
See Wiktionary:
(computing, transitive) To read with an electronic device.
to scan a barcode; to scan a QR code
In order to scan the QR-Code you need to capture the image and then process it.
Usually the capturing of the image is neglected, because it is a trivial step.
来源：https://stackoverflow.com/questions/58238681/are-there-any-different-between-scan-image-through-camera-and-capturing-image-fr