Jpeg decoding result using NPP library

Hello.

I have noticed that there is a question in implementing the Jpeg Encoder by referring to the jpegNPP sample code in the CUDA Toolkit.

We are using the Nvidia GPU to develop a process of HEVC decoding -> jpeg encoding using NPP lib,
There is a problem that the result image of the jpeg encoder using NPP is slightly different from the original image.

I was able to check the following facts during various tests.
  1. Perform jpeg decoding -> jpeg encoding with jpegNPP (sample code)
: obtain the same image as the original
  2. hevc decoding (using Nvidia Video SDK API) -> jpegNPP Refer to the sample code and perform jpeg encoding:
: obtain a slightly brighter image than the original.
  3. Dump the raw pixel which is decoded by hevc decoder
: obtain the same image as the original
  4. Dump the raw pixel after jpeg decoding within jpegNPP(sample code)
: obtain a slightly brighter image than the original.

https://drive.google.com/open?id=18YHb7XVN5_kK_cWfIYPoXPfPXxy-VHse
(The original used here is a 4096x4096 jpeg file, and the image used for hevc decoding was converted to jpeg-> hevc using ffmpeg libx265.)

I guess that there is a problem with the coefficients of the DCT in the NPP library.
If possible, I would like to ask you to check the above, and if it have an issue in the NPP library, could I ask for an update library?

Please leave an answer if you have any data or questions you need for analysis!

Thank you.