There’s a lot more to the file size than the raw and JPEG sizes. Actually, the raw file and JPEG are both extremely compact, achieved through different serious compromises: You can’t view or edit the raw file as is because it’s not RGB, and too much of the original information was removed from the exported JPEG version.
The “natural” file size of an image is:
number of pixels * number of channels * number of bits per channel
A 23MB raw file is typical of a 20 megapixel image, such as cameras capturing around 5500 × 3,600 pixels.
The natural file size for that image in RGB (3 channels) would be around 60MB at 8 bits per channel, or around 120MB at 16 bits per channel. You would get those file sizes if the 23MB raw file was converted to Photoshop or TIFF format. It can be somewhat smaller if compressed, such as TIFF with LZW or ZIP compression.
There are two reasons the photo is only 23MB as a raw file:
- It’s only one channel (the raw data hasn’t been interpreted into RGB yet).
- The camera may apply compression to the raw file. Because if a camera saves raw at 14 bits per channel, an uncompressed 20MP raw image would be more like 35MB, not 23MB.
So it isn’t actually a case of the raw file being larger. It’s really the raw file being much more compact than a fully viewable and editable 3-channel Photoshop or TIFF file, and the JPEG being even smaller because so much editing flexibility has been removed from it.
Does the reduced size of this then-uploaded image make it less amenable to as fine tuning editing process as the RAW image was?
No. For the reasons given above, editing flexibility can’t be judged by file size alone. It has more to do with what format and compression were used.
What makes the JPEG less amenable to fine-tuned editing is:
- It’s been processed to 3-channel RGB, so it lost the ability to be edited with the wider flexibility of the original raw data.
- It’s been compressed using JPEG lossy compression, which is of much lower quality than, for example, the lossy or lossless compression applied to raw files by some cameras. So regardless of file size, JPEG by its nature retains less editing flexibility than raw, TIFF, or Photoshop formats.