I wrote a simple program to convert input RAW data into RGB and display it. The RAW data comes from a DNG file, so I know the white balance parameters and black level values. My basic processing pipeline is as follows:

First subtract the black level from the RAW data, then apply demosaicing, followed by white balance adjustment, and finally perform gamma correction.

However, I noticed some differences between my output RGB image and the TIFF exported by RawDigger in RGB Render mode. Compared to RawDigger's TIFF output, my simulated results appear somewhat hazy - whites aren't as bright and blacks aren't as deep.

I'm attaching download links(https://drive.google.com/drive/folders/1oRoPo7VfpZfrHl7tskpa-H18X0t-LdaY...) for both images for reference:
- The file named "rawdigger.tif" is exported from RawDigger (in RGB Render mode)
- The file named "sim.bmp" is my program's output using the described pipeline
- The file named "exif.txt" is exif info.
- The file named "src.dng" is original DNG file.

In my simulation program:
- Black level value used: 64
- White balance gains: wb_gains = [1/0.5547, 1, 1/0.6563]
- Gamma value: 2.2

Could you please help identify what might be causing these discrepancies?