Bits vs bits..

FeatherMonkey · Jun 29, 2015

Due to present pp workflow I'm forced in to a 8 bit working space(gimp), curious to what I'm losing? I can do all levels, wb, crop, denoise, general sharpening etc.. To be fair I have quite a few bits I can do in my raster editor(darktable).

So really apart from banding what else do I need to look out for? What are the considerations I need to consider does it really matter?

Ysarex · Jun 29, 2015

Are you using Darktable to convert raw files?

If so you should be able to manage color and tone response processing for the most part in Darktable and only use GIMP for things like cloning in which case the 8 bits isn't an issue. For more sophisticated processing in GIMP like masking to adjust local tone, contrast, or color the bit depth becomes an issue. Restricted to 8 bits, your color gamut is reduced enough to cause banding as you've noted which is basically one version of the larger problem that discrete data is forced to posterize in sections of the image -- you lose data. The process of editing a photo is after all destructive and you're forced to lose data; it's all about whether and how you're managing that lose.

Got to take that with a big grain of salt: after all how many photographers are popping JPEGs straight into LR and wanging away on those sliders -- endorsed by Adobe and looks good on Instagram. What you're worried about is less damaging to an image.

There is version 2.9 GIMP which may not be rock-solid-stable but it does work and I've been able to use it without a problem. That takes the concern off the table and would be my recommendation.

Joe

Overread · Jun 29, 2015

Far as I'm aware its mostly banding that you have to worry about. In general things like bit count, colour space, jpeg vs raw isn't all about general day to day editing; its more about the extremes of potential. A higher bit depth gives you more latitude to work with; you can push and pull things more so without a detrimental effect - however in day to day editing chances are you'll be fine.

Of course you'll always get a few shots that have trouble even with minor adjustments. The key is to always keep hold of your original RAW or the original JPEG (the JPEG in an unedited form) so that in the future if you've any great shots that you want to improve with better software you can.

Note Photoshop and lightroom 5 are currently around £10 or so a month from Adobe - its worth considering signing up to get hold to two powerful and key editing programs for what is a very little amount each month (less than you'd likely have spent on film in a month - and these days about one night out down the pub - actually probably a lot less than that)

FeatherMonkey · Jun 29, 2015

Thanks Joe, yes I do use darktable to export, normally to a 16bit png at the mo. You've kind of confirmed where my thinking was at. I am presently doing all pp in darktable.

I just was finding whilst I can achieve some form of cloning using the spot healing tool it wasn't exactly straightforward. Also masking seems a little clunky(wanted the magic lasso of gimp) also fancied playing a little with layers.

I was contemplating getting the gimp dev tree down as I use a rolling release os but figured I'd wait till they rolled it. May still yet but as you noted I can do a fair bit in darktable.

Thanks Overread
I have weighed up ps but tbh as noted above in response to Joe I think I'd get little gain for the expense. From what Joe said continuing my pp workflow in darktable with a final tweak in gimp should work for me.

In regards to internet have to admit for me printing is a goal.