Thanks for the purchase and upload. Were the original files in jpeg? They're quite noisy and do need some leveling or special denoising to get rid of it.
@nikgtasa I double checked and it looks like the original files were in .png. Someone who knows their way around DLSite doujins contained in a .pdf probably could have gotten them out unaltered but I haven't cracked my copy of Acrobat so I went the manual route and extracted through Photoshop/saved as a .jpg