Philippines Wideangle - Filtered & Unfiltered

Too magenta was my thought as well. There is obviously quite a bit of subjectivity and personal preference to be taken into account.

I know Craig feels pretty strongly about this, and I understand the reasoning, but I guess the question is whether from a practical standpoint there is any appreciable difference in quality between images taken using filters or images adjusted in processing. It seems with 14 bit image data, non-destructive RAW processing, tools like U-point in Nik and Capture NX which make it very easy to adjust just the water by itself without masking for example, we have a level of control that is hard to achieve with non-variable filters underwater.

I think it is worth making adjustments to kit, such as these, so that images come out of the camera as close to "finished" as possible. This has the potential to speed workflow and reduce RAW adjustments and Photoshop. There is also the benefit of seeing images looking great underwater, which encourages you to keep working on a setup to try and nail that perfect shot. When things look crappy on the LCD it is easy to swim on.

I certainly would not recommend use filters that overdo an effect (10 or 20 CC seems about right here). And of course things can be adjusted in post, both for filtered and unfiltered shots. But surely it is worth making adjustments to kit to get things as right as we can underwater, if we can.

Alex

I agree with that, but it seems in a case like this unless you get the kit just right without being able to dial in filtration, you may have to land up doing adjustments anyway.

I do think it would be possible to get it right, although I still remain concerned that add the magenta helps in RGB, but could be a real problem in CMYK.

And while you may have to do adjustments anyway, you are starting from a better place. Colour adjustments quickly cause noise in colour gradients, even in 14 Bit RAW (not that I have a 14 Bit camera!). Less is good, if you can. Just because there is a control in RAW that allows you to selectively adjust a colour, it does not mean it is not with penalty to image quality.

Alex

I do think it would be possible to get it right, although I still remain concerned that add the magenta helps in RGB, but could be a real problem in CMYK.

 

And while you may have to do adjustments anyway, you are starting from a better place. Colour adjustments quickly cause noise in colour gradients, even in 14 Bit RAW (not that I have a 14 Bit camera!). Less is good, if you can. Just because there is a control in RAW that allows you to selectively adjust a colour, it does not mean it is not with penalty to image quality.

 

Alex

I know this may be getting a little off topic, and maybe Craig can answer this, but why do colour adjustments in a 'non-destructive' editor cause noise problems? It would seem that when making colour adjustments in RAW one is simply reassigning a digital coordinate within a colour space to any given pixel. Why would say a large colour adjustment create any more noise than a small colour adjustment?

Matt, thanks for posting these! I didn't mean to put you on the spot - take your time and process how you normally would for web presentation. This is really helpful.

Cheers

James

Lots of thoughts:

Large color adjustments amplify noise and quantization (banding) that is already present in an image but perhaps not noticeable. Color adjustments don't add noise themselves. The larger the color adjustment, the more dynamic range is lost so where once the result was smooth you may end up with blotches and banding. Our water is especially sensitive because it is intentionally underexposed to begin with.

The perception of purple comes from removing too much green. Because there's always some red in the water (since "blues" aren't fully saturated) removing too much green converts some of the "white" in the water to "purple". Magenta is added in the CMYK sense but it is addition through subtraction. Alex's concern over appearance in CMYK prints is real, but if we're seeing an image on a calibrated system and approve then having the print come out bad is a failure of the process. Nevertheless, if that's the process we use then we have to be mindful of it.

If you are willing to accept selective color adjustments as an alternative to filters then you should be willing to accept selective color adjustments in addition to filters. It is better to use a CC30 filter and back off a little than to emulate the entire filter effect in software. As Alex says, it is valuable to get the image as close to what we want before editing.

I've said in other threads that filters are a blunt instrument. You can't fine tune them during the dive so you need to choose carefully. I feel that a CC10 set is not enough effect to mess with but others may feel differently. I believe that 20-40 is likely the range that is most effective based on conditions. What filters an individual chooses to travel with will depend on the water he expects to see. I wouldn't argue with someone who preferred CC20 over CC30 but if I dove in pea soup I'd do something different. The more aggressive you are with your filter the more commitment you make to careful post-processing. A CC30 filter is not a use-and-forget device.

One of the things to consider here is that we're accustomed to seeing images a certain way. It's easy to see an image as being too purple when you are predisposed to expect green. It can be hard to be objective with this issue. We have to be careful, though, in these comparisons not to confuse matters by playing with overall white balance. We are looking at background rendering but we have to make sure that foreground is staying consistent.

I agree that some of James's images may push the effect too far but it's hard to tell in web images. If you aren't dealing with that problem from time to time then you aren't pushing the technique hard enough.

If someone is dedicated enough to try multiple strobe filter strengths, I'd point out that they don't need to match each of the strengths with the lens filter. Let the raw converter handle the small mismatches.

Unfiltered (and direct from DPP) - both from Puerto Galera.