0

The Pi Camera v2 has 3280 x 2464 pixels, which gives 8081920 pixels. It is my understanding that a PNG-24 means the pixel supports a 2^24 color depth. It is also my understanding that a PNG-24 means 24 bits per pixel (bpp). This would mean that for a single PNG-24 image, there are 8081920 pixels x 24 bits/pixel = 193966080 bits or about 24.24576 Megabytes. However when I capture an image using -e png encoding, I get an image of about 2.162 Megabytes, which is about 10x smaller than predicted. What am I doing wrong? Can someone help clarify how to predetermine the file size.

  • The wikipedia entry explains how png files use lossless data filtering and compression to reduce size. – meuh Sep 10 '17 at 14:41
0

Your calculation would fit to an uncompressed image file format (e.g. BMP), but PNG is compressed - although it uses lossless compression, so gives the same result as a large uncompressed format would give.

Predicting the size of a resulting PNG file could only be done by knowing something about the image content at the time of the prediction, approximating by the mathematical methods of PNG compression.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.