924 - The Art Of Not Seein' Red

No censorship today. Promised 🙂

Instead I want to talk about a thing that I just did in Photoshop and that may be of interest to you. I probably should make a proper tutorial with screenshots and step-by-step images of it, but I am too tired. My day was rather hectic, I am on the train to Carinthia now and I will stay there for a week, and just like always before I go on vacation, things get really awry. In fact I fixed the last bug 15 minutes before I left. Let’s hopethat was it 🙂

Enough of work. Let’s look at the Image of the Day now. I shot it this morning against extreme backlight. To the left is the original out of the camera. Quite dark, huh? You should really click both to appreciate the difference.

Honestly, I didn’t think that I would be able to fix it. In that extreme contrasty light, there could not possibly be any detail left in the shadows, could it? Well, turned out it could. Obviously under these conditions, shooting in 14bit RAW is a real life saver.

I converted the image to a very flat file, just to make sure that I get every bit of detail that I can. Then I copied the layer, treated it with Noise Ninja, and changed the “Blend If” sliders to 0% in the highlights and 100% in the shadows, essentially giving me noise reduction with probably a little loss of texture in the shadows, while keeping the highlights crisp.

Eventually I intended to push saturation and put contrast back in, but before that, I wanted to heavily push local contrast. There are multiple ways to do that. One is, to use the tone mapping algorithms of some HDR tool like Photomatix Pro or Essential HDR, the other is, to use a specialized tool like PhotoLift, and finally one could even employ the good old unsharp mask filter to enhance local contrast with a high radius and a low amount (HIRALOAM, as Dan Margulis calls it). In this case I used PhotoLift, and I used it on a merged copy of the layers below, specifying a very high amount of local contrast (160 on their scale) and -90% global contrast. Thisyielded a ridiculous image, just like an HDR completely overdone, almost local contrast only. Then I changed the blending mode to “Soft Light”, and - voilà - back were contrast and quite some saturation.

At that point I recognized, that I would not get away with this image without further tricks. I had steepened contrast in the low tones so enormously, that there was now a red halo along most high-contrast edges. It’s not the lens, the Sigma 70/2.8 has almost no chromatic aberrations, neither lateral nor longitudinal, and of course not at f8, no, this must have been a sensor artifact due to the incredibly high contrast. Of course it was negligible in the original, but after so much amplification, it was clearly an issue.

What I did, was to create an edge mask. I have an action for that, because I use edge masks often to restrict sharpening to edges only. Basically it involves Photoshop’s “Find Edges” filter, desaturating, inverting and slightly blurring the result, and then manually applying levels, to find the right balance between edges and background.

I created such a mask, but only this time I did not apply it to a sharpening layer, but instead to a “Hue/Saturation” adjustment layer, and in that layer, I desaturated the reds to -80%. The result was striking. All the halo artifacts were gone.

Without any danger, I could now further increase saturation by a combination of “Hue/Saturation” layers in different blending modes and with different “Blend If” options. For more on that, please see my tutorial in “683- Welcome To The Republic”.

Finally I used my currently favorite sharpening method, involving a copy/merged layer, setting it to “Luminosity” mode, sharpening with 180/0.5/0, adjusting the “Blend If” sliders by splitting the darks and pulling them up to 63, splitting the lights and pulling them down to 128. In this case I even lowered opacity to 70%. The result was a very crisp sharpening in the mid-tones, completely without any sharpening artifacts laike halos. Ask me if this was too quick, I may explain it in a tutorial of it own.

EDIT: I normally don’t do that, but only at home did I recognize how laptop display and reason had failed me: The laptop can’t display real, deep blacks, and I had not payed attention to the histogram. The image as displayed yesterday evening was much too timid in the dark tones. I salvaged that by creating a CMYK image from a merged copy, taking the black channel, and multiplying it into the low half tones, with full blending in the blacks and no blending from medium gray upward.

Sorry. From here on it’s again the original text of the post.

The second image did not have any problem like #1. In fact I have shot it in flat, even light in a shadowy street. It did have a small amount of purple fringing though. Not much, but at f4, a certain amount of purple fringing is not uncommon along contrast edges on chrome parts. It may happen even with very good lenses like this Sigma 70/2.8 Macro lens.

Honestly, it wouldn’t have been necessary at all, but as I already was at it, I did the same trick again, this time to fight purple fringes. I added an edge mask to a “Hue/Saturation” layer, and with that layer I desaturated magenta and blue to -90%. If I had had those colors anywhere else in the image, I could have painted in the mask, to restrict the effect to the chrome areas, but in this caseit was not necessary.

Well, that’s it for today. I’m amazed that I managed to write that much 🙂

The Song of the Day is “Seein’ Red” by jazz clarinetist Edmond Hall. I have it on disc 31 of “The Ultimate Jazz Archive”, that wonder weapon in all musical fights, but as this 168 CD collection may be a tad expensive in the US (did I ever mention it cost me 99€ only), I have also found the album “Profoundly Blue” for you. It contains the song as well as another album that you can hear at Deezer. Enjoy.