Month: December 2015

Curves

In Pt. 3 we looked at the Levels tool. Now let’s turn to Levels’ big sister: Curves. The Curves tool works well for colour photography but it is especially useful in B&W photography because it can be used to make fine adjustments to tonal values in an image. Where Levels offers three controls, black, white, and midtones, Curves offers up to fifteen adjustments points.

The Curves tool scares a lot of beginners because it’s not as intuitive as Levels but Curves are quite logical once you get the hang of them. Alas, there is no proper Curves tool in Photoshop Elements, though there is a Color Curves tool that is really little more than Levels presented another way. Photoshop and Gimp have a fully-featured Curves tool.

So, let’s take a starting image, a cell-phone shot I took in a coffee shop:

Converting this to B&W using Channel Mixer and using the Green filter preset, I get this for a starting point:

Because of the inherent contrast in the image, it’s already looking pretty decent, though it’s a bit dark. To tweak the image I turn to the Curves tool, which looks like this in Photoshop:

So, where’s the curve? All we see is a straight diagonal line going from bottom left (blacks) to top right (whites). The answer is that we start with this straight, diagonal line and pull and push on it with our mouse to see what effect it has on our image.

Starting then, on a duplicate background layer, let’s call up Curves and tweak the line around a little and deliberately overdo it to see what effects we can get.

I’ve placed two anchor points on the line to make the kind of S-shaped curve that would normally be just about right to add some zing to the image, but in this case the image is already contrasty and the adjustment makes it overly contrasty, unless you’re going for a silhouette image. The dark areas in the image were already quite dark and I’ve pulled them down into the blacks and have lost a lot of interesting detail.

To reset Curves back to its original state, click Option-Reset (on a Mac) or Alt-Reset (Windows). Now let’s do something wild and really distort the image:

This time we get an image that is distorted and nearly solarized. There may be times when this might be just the right kind of treatment for an artistic presentation, so keep in mind you can do experimental images using Curves.

Now, let’s Reset Curves, and try for a more conventional B&W image:

Notice I’ve used 5 anchor points to give Curves a boost to lighten up the midtones but keep the blacks a deep, rich black. The final image, then, with a little sharpening added, looks like this:

For practice, try adjusting an image (always on a layer) with first the Levels tool, then the Curves tool, to get a feel for the difference between them. The Levels tool is good for most images, but the Curves tool offers more sophistication and is especially useful for images that are hard to get just right.

For more detailed information on using the Curves tool, here are some excellent online articles you may wish to read.

Next time we’ll explore Photoshop’s secret weapon: Layer Masks.

Introduction to Layers

It’s layers that separate Photoshop pros from the novices. The idea of layers is simple: if you stack, say, a copy of your image on top of your original image, and both are transparent, you can look down through them and they look like a single image. If you change things on the top layer, it shows down through both images, but the underlying original image remains untouched. Often you will add even more stacks to the layers, each doing something else to the composite image. Then when you’re happy with the results, you flatten all the layers down to a new single-layer image.

This only hints at what layers are all about and, because a full study of layers would be a course on its own, I’ve posted some links at the end that you can follow to learn more about the flexibility and artistic potential of layers.

The best way I can introduce layers is to show how they can be used in a typical colour to black-and-white workflow. So let’s take as an example the following photo that I shot because I thought there was potential for a good B&W image in the curves and textures.

As a colour shot, this is pretty drab. It was taken on an overcast day with no sunshine to play on the lines, but in the B&W conversion we’ll use the Levels tool to bring more contrast to the image. In this procedure I’ll be using Photoshop Elements, v.14, as my editing tool.

Let’s start by creating our first layer. In Elements, click on the Expert tab, then click on Windows->Layers to bring up the Layers palette, then click on Layers->Duplicate Layer and you’ll get a layout like this:

We’re now looking through two layers and will do our B&W conversion on the top layer. To turn the image into a B&W using Elements 14, let’s call up the Enhance->Convert to Black and White tool, which corresponds to the Channel Mixer in Photoshop and Gimp, discussed in Pt. 2. Mix the Red, Green, and Blue channels together via the sliders until you get a nice range of mid-greys. If you click off the Eye icon on the top layer, you can see that the bottom layer is still in colour. This allows you to switch back and forth between the top “adjustment layer” and the base layer or “Background” as the program calls it.

Technically we now have a B&W image, but it has no pizazz, nothing at all that grabs the eye. Nonetheless, it has potential. So let’s go with it: Right-Click on the top layer and select Flatten Image. This, then is our starting point for B&W.

So, the key to this is that you should always work on an adjustment layer which can either be a copy of the base image or, in recent versions of Photoshop and Elements, a specialized Layer Adjustment Tool. Elements (as well as Photoshop) has such a tool for Levels, so in Elements click on Layers->Adjustment Layers->Levels.

Notice that it’s put a new kind of layer on top of the base layer and labelled it Levels.

In terms of post-processing, it’s at this point that art joins technique. Where we go from here is a matter of taste and preference and no two photographers will come up with exactly the same finished image. Let’s consider what we have to work with.

The dark shadows under the curved steps at the top of the photo are completely black, without detail, so there’s no worry about preserving subtle detail. Overall the middle greys are too light and dull. The highlights need to be a little brighter. The image has nice lines and interesting texture. What we need to do is bring out these, and that’s what we’ll do with the Levels tool.

Look at the histogram of the Levels tool, especially where the markers lie under Input Levels. There’s a black marker at the far left, a middle grey marker in the middle, and a light grey marker under the highlights.

Play with these three sliders, and really lean into them. Slide the black marker far to the right, then Reset and move the highlight marker far to the left. Observe what this does to the image, greatly exaggerating the effects. Slide the middle marker to the left and then the right. Somewhere in all this there are combinations of adjusting the markers that will make the image jump out at you. You just have to find them. Some images require a lot of adjustment and some just need a touch of this and that to bring it to life. This is what I came up with for my interpretation:

Notice that I brought the highlight marker into the area where the histogram ends on the right, that I adjusted the middle marker to the right to bring down the middle grey tones and that I boosted the blacks a bit by bringing in the black slider slightly into the middle. One of the side effects of this is that it adds much more contrast to the B&W image:

Notice that after getting the image most of the way to what I wanted, I flattened the layers and have a single-layer image again. This is just about good enough to post on the web or print off, but there’s another step I like to include before calling it done. One of the things experienced B&W photo printers do in the chemical darkroom is to slightly darken the edges and the corners of the image, with burning-in techniques, because this subtly draws your eye to the centre of the photo. You can still do it that way with the Burn tool in Photoshop and Gimp, but Elements doesn’t include the Dodge and Burn tools so we’ll recreate this effect by adding a slight vignetting with a built-in filter called Correct Camera Distortion:

One of the tools in this filter is the Vignette slider.

First duplicate the Background layer, then invoke the Correct Camera Distortion filter, and, looking carefully at the image, slide the Vignette slider slightly to the left. For the purposes of learning what the tool can do, move it far to the left. Find your visual sweet spot, then click the Eye of the adjustment layer off and on so you can confirm how much vignetting you’ve added to the image. Again, there is no right or wrong, but you will often see beautiful B&W images that have heavy vignetting added. Whether you want to be subtle or obvious is up to you, and it depends on the image.

My final interpretation of the image, with obvious vignetting, is this:

Now that you’ve been along for a walkthrough of this image from colour to basic B&W to final B&W using Levels and vignetting, you’re ready to start practicing on images of your own. Although working on layers may seem complex at first, once you develop the knack for it, it doesn’t take long at all, and the more experience you gain with layers, the more you’ll be prepared to tackle advanced layer procedures.

In Pt. 4 we’ll take a short breather from the technical side and look at the types of images that make natural studies in B&W. In the meantime, if you find yourself interested in layers (and I hope you do), here are some sites, and some books, to help you on your way:

• Web page tutorials
• YouTube Video Tutorials
• Katrin Eismann. Adobe Photoshop Restoration & Retouching (4th Edition)
• Katrin Eissman et al. Real World Digital Photography

Good luck, and we’ll be revisiting layers again.