Fix: pixel data mismatch

[ducquangkstn]

Sometimes, the VL of pixel data does not match with calculated value. (I can not provide the sample file to test this)

• In this case, we want to return an error rather than continue to parse and returns an EOF error (very hard to debug why)
• This MR also adds a flag to allow ppl to skip the pixelData and mark it as Encapsulated.