We’ve had quite a journey with this whole histogram and curves ordeal:

• How to Read Image Histograms
• Photo Editing With Histograms: 6 Basic Settings
• How Well Do You Know Your Curves?
• Photoshop Curves Video Tutorials
• Linear Curve Adjustments and Histograms
• Nonlinear Curve Adjustments and Histograms

And now I’d like to wrap things up with a few tips, tricks, and things to avoid when using curves. It’s a fairly simple tool once you begin to work with it and understand it, but there are a few non-obvious items worth pointing out.

photo credit: Fifi LePew

TIPS

We’ll start off with a few generic tips for working with curves, then we’ll move on to the some of the more detailed stuff.

• Always work with 16-bit images to avoid posterization.
• In Photoshop, utilize layers and adjustment layers for non destructive editing.
• Use the color channel adjustments to correct color cast.
• Start subtle in ACR/Lightroom (or with an adjustment layer in Photoshop), then bump it up or add another layer if you need more.
• In Photoshop, use a levels adjustment first rather than a linear curves adjustment, then go to curves for a wider range to work with.

TRICKS

photo credit: garethjmsaunders

Here are a few tricks for the ACR/Lightroom interface under the “Point” curve.

• Hold Ctrl and mouse over the image to see where the tones lay on the curve/histogram.
• Ctrl+click over the image to set an adjustment point on the curve.
• Ctrl+select adjustment points on the curve to delete them.
• Ctrl+Tab to move between adjustment points without using the mouse.
• Shift+select multiple existing adjustment points if you want to grab more than one at a time.
• Shift+click over the image to set your neutral point for white balance (this works outside of the curves dialog too).
• Shift+arrow keys to move selected adjustment points by 10 rather than 1.

And then we have a few general tricks:

• Use extreme curves adjustments to separate tones for creating masks. Then remove or turn off the adjustment layer once you have the mask. (tip via Niels Henriksen)
• Use curves in LAB mode on the lightness channel to minimize saturation effects of adjustments.
• Boost your saturation using LAB mode curves adjustments on the A&B channels.

photo credit: AlmazUK

THINGS TO AVOID

• Watch for vertical sections in your curve — that produces an extremely high contrast and you lose all midtone data in that area.
• Watch for horizontal sections in your curve — that produces zero contrast and you lose all midtone data in that area.
• Too many adjustment points will be difficult to manage, just use what you need.
• Avoid inverted slopes, they invert the tones. Can you roll a ball from the upper right point of the curve to the lower left (without relying on momentum)? If not, you’ve inverted a section of your curve.
• Don’t clip your shadows and highlights (unless that’s what you really want to do). Keep an eye on your histogram for this one.

I’m sure there are a few hundred other tips and tricks out there for using curves, but I don’t know them all and I couldn’t cover them in one article even if I did. These tips, combined with the previous articles linked at the top, should keep most of you busy for a while. And if you’re looking for more, here’s my final tip on the subject:

Experiment. Try things out, push buttons, make mistakes, and keep learning.

The last article on curves looked at linear adjustments and how those adjustments affect the image and the histogram. So now we’ll take a look at some nonlinear adjustments within the curves adjustment tool found in many photo editing software packages.

We’re basically building on our basic understanding of the histogram and our knowledge of linear curve adjustments to take the next step into nonlinear adjustments (the curvy curves).

NONLINEAR MANIPULATIONS

What I’m going to show here are some very basic curves at each extreme. The single bend and double bend curves are most commonly used during post-processing, but these are not the only options. Curves can have a large number of set points, bends, and inflections — it’s just not feasible to cover every possibility in an article like this.

SINGLE BEND CURVES

The simplest form of a nonlinear curve is accomplished by moving a mid-tone location toward the upper left or lower right corner, forming a basic arc with a single bend. Essentially, your black and white points remain fixed while your mid-tones become lighter or darker (aka: brightness). Also note that one end of your tones will take on more contrast while the other end will lose contrast due to the change in slope of the curve (remember: vertical = high contrast, horizontal = low contrast).

This can be used to brighten or darken the overall image if you want to maintain your highlights and shadows at their current values.

DOUBLE BEND CURVES

Also known as the “S-Curve”, this curve manipulation pushes one section of tones brighter and another section of tones darker (aka: contrast). Again, you can maintain your black and white points, but you also maintain some middle tone where the curve crosses the diagonal. On the note of contrast again, be aware that you will sacrifice contrast in one area to gain it in another.

This can be used to raise or lower the contrast of the overall image with a focus on the mid-tone areas. The bright/dark tone changes of the highlights/shadows are amplified by the mid-tone slope change — so it doesn’t take much to really change the contrast.

APPLYING NONLINEAR CURVES

The beauty of the curve adjustment is that you have such a wide range of possibilities — much more dynamic than a single slider adjustment. To apply curve adjustments, you simply click a location on the curve and drag it to the desired location. The curve will bend on its own based only on your set points. You can continue to add set points until you have the desired result.

Using the example image above (middle of series), here’s one possible curve that combines linear, single bend, and double bend curves. Keep in mind that I haven’t applied any basic adjustments and what you’re seeing is pure curves from an unprocessed raw file (except for the b/w conversion).

Notice that I used a double bend curve to increase contrast. Combine that with a single bend curve to increase brightness. And combine that with a linear adjustment to set my black and white points. I’ve also placed several extra points on the curve in order to bend it into the shape I wanted while maintaining a smooth transition.

As you work with curves, you’ll noticed that they sometimes have a mind of their own. Extra points will help shape the curve and provide you with the ability to make the adjustments you want. On that same note, too many set points can lead to choppy and lumpy curves. Non-smooth transitions generally begin to produce strange contrast artifacts that are easily seen in the image.

A Guest Post by Pye of SLRLounge.com.

Introduction

If you have been anywhere near the photography world in the past couple years, I am sure you have heard of HDR by now as there have been countless tutorials floating around on how to create HDR images using 3 bracketed exposures in programs like Photomatix and Photoshop. However what if you don’t have your tripod or if you are shooting a scene with moving subjects, yet you still want to create an HDR type shot? Well, good news, it is possible.

This tutorial will teach you how correct and produce a single RAW image into an HDR-like masterpiece using only Lightroom! That’s right, Photoshop skills are not even needed for this tutorial.

Before you get started, you can download the RAW image used in this tutorial by clicking here.

Image is provided courtesy of Lin and Jirsa Photography.

Shooting the Image

Before we get into the actual post production steps, let me quickly give you a background of the image and how it was shot. I always shoot in RAW format simply because it provides vastly more tonal information than the compressed JPG format. What does this mean? It means that we can do much more to the image in post production before the image quality degrades. Your ability to alter Color Temperature, Exposure, Brightness and Saturation is much more limited with JPG files in comparison to RAW files. Bottom line, if you are trying to create an HDR look from a single image, you MUST SHOOT IN RAW.

What you see below is the RAW file directly from a Canon 5D Mark II. The crucial component for shooting a single shot image that is going to be turned into an HDR shot is to shoot it so that you are not clipping any shadows or blowing any highlights. This typically means that you are going to be anywhere from 1-2 stops under exposed in order to save most of the highlights and still keep detail in the shadows.

When you are getting used to this process, it is wise to take a few different shots of your scene at different levels of exposure in order to get the hang of just what level of exposure you need. If the shot is too bright, you will have no details left in your highlights, where as if you shoot the shot too dark, then you are going to create too much noise brightening the shadows.

Image Metadata (Canon 5D Mark II, EF 17-40mm F/4L USM @ 40mm, 10 seconds, F/11, ISO 100)

RAW files will always look dark and murky from the camera since there is no post production applied to the image. Keep in mind that the camera LCD preview will apply some post processing settings to the image when you are previewing them, so I recommend that you turn on your highlight alert to make sure you didn’t blow your highlights or clip your shadows. You will notice that the shot above is exposed so that we can still see color in the sky, while still seeing most of the detail in the shadows under the dock.

If you haven’t already done so, download the image and load it into Lightroom. The RAW image you see above is “zeroed out” meaning that every Lightroom slider is set to 0. Lightroom will typically apply default settings to each image, so you want to make sure your image is zeroed out as well, otherwise it will look differently.

Processing the Image

Step 1) Brightness +80 - The first thing I typically do when processing an image is to typically dial in an approximate Brightness level so that I can see the correct effect when applying other adjustments. I am going to start with +80 as a baseline, however, I will revisited the Brightness to make sure it’s correct once our Contrast/Black levels are adjusted. During brightening I am paying more attention to the brightness levels of the darker areas than the sky and water since I can burn those down later.

On a side note, I always resort to using Brightness before Exposure. Reason being that Exposure affects highlights more than shadows and mid-tones, while Brightness adjusts all of the tones equally. You should now see something like the image below.

Step 2) Contrast +100 – I love my landscapes to really pop and so I love using a lot of Contrast in my shots. I am always careful to make sure the shot doesn’t look faked, but even at +100, I don’t think it’s too much. You should now see the following.

Step 3) Blacks +7 – Now, I am going to dial in my Blacks to make sure the blacks in the scene are truly black versus a dark shade of grey. During this part you want to be careful not to clip (lose detail) too much of the shadows in the scene by taking your Blacks too high. If you press “j” you can see which areas are clipped as they will be highlighted in blue as shown below where blacks are set to +17.

Some time ago I wrote a post on batch resizing images in Photoshop and another on resizing in Lightroom.

One of our readers wrote to me recently explaining that he is using Photoshop Elements and that the resize feature in Photoshop does not work in Photoshop Elements. He is correct, but there is a way of batch resizing in Photoshop Elements and here’s how to do it.

Step 1

In Photoshop Elements, choose File > Process Multiple Files. This opens the Process Multiple Files dialog.

Here you can select which images to process. You can select either a folder of images, all opened files or you can click import and import images from an external device such as a camera card.

Typically, the best option will be to place all the images in a folder and process the files from that folder. To do this, click the Browse button opposite the Source box and choose the folder to process. Enable the Include All Subfolders checkbox if desired.

Step 2

Select the destination folder for the resized images (you can create one from this dialog), or, if desired, select Same as Source.

In the file naming area, select Rename Files if this is desired. You can then choose the naming convention such as typing a document name and the sequential numbering system to be used.

Step 3

In the image size area, select Resize Images as that’s what we came here to do.

Select Constrain Proportions as you will want your images to be resized in proportion and not skewed or distorted out of shape.

Now type the largest Width or Height to use for your resized images. If you enter 600 for the Width you will be unable to enter a value for the Height and vice versa. This is because you can only set one value – width or height (in this situation this resizing tool works differently to the corresponding tools in Photoshop and Lightroom).

So if you enter, for example, 600 as the Width all images will be sized so their width is 600 and their respective heights will be adjusted in proportion. Portrait images will be taller than 600 pixels and Landscape ones will be shorter.

Here too you should set the resolution for the images. If you plan to send your photos to an online sites for printing, you may want to match the resolution to what that site requires. For the web select 72 dpi.

Step 4

To convert the files to a different format or to compress them, from the File Type dropdown list, select the file format to use. For JPEG format images, you can choose Max, High, Medium or Low quality.

Step 5

You can also apply a Quick Fix to your images as you process them. These fixes include Auto Levels, Auto Contrast, Auto Color or Sharpen.

You can also apply Labels to your image such as adding a watermark or caption by configuring the options in the Labels area.

When you are done, click Ok to process the folder of files or the group of files that you had selected for processing.

Tip

If you want to resize images so their longest edge is a set value such as 600 then you will need to presort Landscape and Portrait images into separate folders and process them separately.

Post from: Digital Photography School – Photography Tips.

Batch Processing in Photoshop Elements