PNG files in photography workflow

Question

I shoot Fujifilm and like the builtin film sims. Capture One, does a good job at reproducing them, but I find sometimes Fuji JPEGs better, particularly when some proprietary features (e.g Color Chrome FX) or alternative film simulation recipes are used, since they cannot be reproduced as is in a photo editor like C1 (only X Raw Studio can help somewhat).

Some folks do light basic editing (crop, perspective & lens correction, ...) of the jpegs but the operation is lossy, since every time you do something on the jpeg file, you lose some image quality.

I do sometimes convert the JPEGs to PNG and edit the latters in C1, considering that once converted in PNG, you kinda "freeze" (in theory) the image quality of the original JPEG, until you do a final conversion to JPEG.

I didn't find information about such a workflow (JPEG > PNG > Edit > PNG).

So questions are:

• Does it make any sense and offer the possibility of some limited of the JPEG file editing without loss of quality ?
• Does editing of a JPEG file in Capture One preserve its original image quality ?

Answer 1

I think your understanding is incorrect. Converting a JPEG to PNG doesn't magically aid in quality preservation as you edit an image. Essentially, when an image is opened in an editor, the filetype that the image had been stored as is irrelevant; you are simply dealing with pixels that each have a RGB value. (These are 8-bit values in the case of JPEG.) When you push these pixel values around (i.e. applying edits to the image), new RGB values are calculated for the pixels. It doesn't matter if the image was a camera-original JPEG file or a PNG file saved from that original, the RGB values are going to be the same.

The difference comes when the image is re-saved as JPEG. It's at that moment that lossy compression is applied for JPEG files, and that's where quality is theoretically lost. If you were to save as PNG or TIFF, no lossy compression is applied. (Personally I prefer TIFF – probably things have changed, but there was a time when PNG didn't support colour profiles.) Re-opening these 2 hypothetical JPEG / PNG files can result in different RGB values for some pixels. This loss in quality however, based on re-saving a high-quality JPEG file as a high-quality JPEG file, one time, is negligible. You won't notice it. Still, if you intend to apply further edits, it makes sense to save your file using an image format that doesn't apply lossy compression.

The big difference is between 8-bit and 16-bit files. When you push pixel values around in a 16-bit file (i.e. applying edits to the image), then new RGB values are calculated with more precision, and there's more "room" for gradation between colour values. Especially for editing, 16-bit images are more, let's say, "desirable" than 8-bit images.

This explanation is a simplification, but hopefully adds something.

Answer 2

If you want manufacturer-quality editing, filters/LUTs etc, use the manufacturer's software.

If you want to edit further after that, use 16-bit TIFF.

Only ever go to 8-bit at final export.

Yes, this makes for some heavy file sizes, but HDs are cheap these days.

^{A bit breif for an answer, but didn't want to post as a comment …and didn't really have much else to add;)}

Answer 3

Not sure if you considered it but each major camera manufacturer has their own raw file developing software which should produce same image as in-camera JPEG (you might check it yourself using raw+JPEG pairs of images produced by camera). For sure Fujifilm has it too and it provides a lot of output options. It's named X-RAW Studio in your case.

Answer 4

To add to the other answers; if you want your edits to be "lossless" you should convert the file to a 16bit tiff and edit it in C1 using layers and layer masks; keeping the original file/base layer unedited.

That way all edits can be reverted without loss of the original data. Save the the working file tiff with lossless compression with all layers.