The difference might not be in the data contained in the comparable uncompressed 48-bit TIFF and DNG files, but rather in the way *Imagemagick" is interpreting that data to present it on your 24-bit screen.

I'm not sure how it works out with data from a scanner, but with raw data from a camera that includes proprietary information such as data from masked pixels gathered on the sensor, converting to DNG does "bake in" the black point and white point of an image file by throwing away the information from the masked pixels as well as the other proprietary data that some sensors collect.

The difference might not be in the data contained in the comparable uncompressed 48-bit TIFF and DNG files, but rather in the way Imagemagick is interpreting that data to present it on your 24-bit screen.

I'm not sure how it works out with data from a scanner, but with raw data from a camera that includes proprietary information such as data from masked pixels gathered on the sensor, converting to DNG does "bake in" the black point and white point of an image file by throwing away the information from the masked pixels as well as the other proprietary data that some sensors collect.