Category Archives: Post-processing

Digital Camera Sensor Resolution and Print Sizes

After a presentation to the 4th annual Western North Carolina Foto Fest in Montreat, NC, in September 2013, a couple participants asked me to post my two slides showing the resolutions of digital camera sensors, and effect of resolution on print sizes.

The first slide is reproduced here:

Typical Image Sizes in Pixels

Typical Image Sizes in Pixels

As you can see, a 1.0 megapixel (mp) camera has more resolution than the old NTSC television and more than most PC displays used to have. You might be surprised that a 3.0 mp sensor has more resolution than HDTV! Even more shocking, perhaps, is that the incredible iPad with Retina display has a resolution of 2048×1536 pixels—-exactly what you could capture with a 3.0 mp camera.

So what in the world do we need a 12 mp or 24 mp, or goodness knows, a 36 mp sensor for? That’s where the second slide comes in:

Print Sizes at 240 dpi

Print Sizes at 240 dpi

This chart shows the native print sizes you can make at 240 dpi from the various digital camera sensor resolutions. (Note: I’m not suggesting that you always print at 240 dpi, but that resolution was chosen as a constant to make a comparison. Selecting the appropriate print resolution is a topic unto itself.) Continue reading

My Post-Processing Epiphany

For a time, I was disappointed that so many of the photography enthusiasts I encountered when judging for or speaking to camera clubs, or when co-teaching photo workshops, didn’t seem to take their photography seriously enough (in my world) to want to master post-processing. More than ever before, it seemed, digital photographers were looking for the easy way out when it came to post-processing. I wondered why.

Maybe this harkened back to the color film days, where you mailed or dropped off your rolls of slide or negative film, and then were either pleased or disappointed by the slides or prints you got back. Except for B&W negatives in the wet darkroom, there was no post-processing done by most film photographers. If you weren’t happy with your prints, you could ask the lab to reprint them. That may or may not get you what you envisioned. If you weren’t happy with your slides, you were out of luck. But if the negatives or slides just weren’t right, your only option was to reshoot, if you could.

But it’s all digital now. So maybe it was the steep learning curve for mastering Photoshop. Maybe it was the result of the proliferation of plug-ins promising perfection at the click of a mouse button. Maybe it was short attention spans in a fast-paced society. Maybe it was simply laziness.

Maybe it was none of those. Continue reading

Contrast and Saturation Basics

When you first open a properly exposed Raw image, it usually looks flat and lacks punch. It’s nothing at all like you saw when you clicked the shutter. That image now requires processing in Photoshop’s Adobe Camera Raw (ACR), Lightroom, or the Raw converter of your choice. You can, and should, adjust the exposure, set the global white balance, capture sharpen, handle noise, etc., in ACR or its equivalent, but a discussion of Raw processing will be for future posts. For now, in general, just make sure you leave some room at the dark and light ends of the histogram, if possible, and leave the image a little flat to open in Photoshop. It’s always easier to add than to remove contrast and saturation in your final Master image.

So, what is the difference between contrast and saturation, and how do you add one, the other, or both?

Contrast is the difference between light and dark tones. You can also think of it as the separation between the shadows and highlights. An image with low contrast is said to look flat or dull, while high contrast makes an image look punchy or “contrasty”.

Saturation is the depth or intensity of the color. The lower the saturation, the less intense are the colors. They can look weak and pale. If you fully “desaturate” the colors, you end up with a monochrome, or black & white, image. On the other hand, if you increase saturation too high, the colors can become “oversaturated” and look unnatural.

To illustrate the effects, let’s use an example from Antelope Canyon. As you may know, Antelope Canyon was created by erosion of the Navajo Sandstone. As sunlight streams in from the top, it both reflects and directly illuminates the intricate walls and surfaces in the narrow canyon. With your camera’s white balance set on Auto, the prevalent orange hue becomes sort of a grayish orange in the Raw image.

We’ll start with the unprocessed Raw image, shown below. As you can see, it’s rather flat and dull.

Continue reading

It’s Okay to Crop – Sometimes

I can hear several of my friends laughing even before reading the rest of this. After years of my staunch (they might say unreasonably stubborn) aversion to cropping, they’ve prodded me to realize that the camera’s default image shape doesn’t always result in the best image.

It’s still my preference to get everything just the way I want it in the camera, especially with landscape images. But now, I’ve come to appreciate the benefits of the occasional crop.

Sometimes, you have to crop to fit certain requirements for a website, client, contest, or publication. (Heck, even my header image on this site is cropped from a full frame.) Other times, a judicious crop just suits the image better than the camera’s default shape does.

Now this is not a license to “shoot loose, and crop later”! That’s lazy, sloppy, reduces the resolution of your images, and is bad practice.

Here’s an example of when cropping worked better than the default image shape. When she was a little puppy, my BFFFF (Best Furry Friend Forever, Fredo) came by my office for a visit. Well she didn’t come by on her own; her Mom brought her over.

Fredo Singing (full frame). Click on image to enlarge.

She was sitting in one of the conference room chairs while I was taking pictures of her. She was being so tolerant, it was time to reward her with another treat. I loved the expression on her face in this picture as she anticipated the treat. It looked like she was singing.

But as a rectangle, the photograph was cluttered and distracting. I knew a square crop would eliminate the distractions, focus the attention on Fredo, and makes it look more like she’s singing. I framed the image so there would be enough room around her so I could crop it square, yet still retain a sense of place by including recognizable portions of the chair and table. I also placed her to the left side in case the rectangular shape worked as well. It didn’t.

Fredo Singing (square crop). Click on image to enlarge.

One of my main influences for thinking in terms of the square image is my friend and mentor Charlie Waite. For most of his professional career, he made landscape images using a Hasselblad film camera, which yielded a square image. A square format image often tells a significantly different story than a rectangular one.

What I’ve learned is that cropping an image to improve its composition doesn’t necessarily mean the image was not composed well when the shutter was clicked. Sometimes, it’s just what you need to tell your story in the best way.

Maybe it’s just that a puppy taught an old dog new tricks.

 

Chosing a Color Space

When converting a RAW image file (and you are shooting RAW, right?), you have a choice of color spaces and bit depths to work in. Unless you’re not going to do any post-processing, and are only making a JPEG, you should work in 16-bit. (Hmmmmm, this might be the subject of a future post. For now, just trust me.)

Just as strong a recommendation can be made for using the ProPhoto color space. When converting a RAW image, the most common color spaces used, from smallest to largest, are sRGB, Adobe RGB 1998, and ProPhoto. If you shoot RAW, your image doesn’t have a color space assigned until you process it in your RAW converter of choice. (Yes, even if you set your camera’s color space to sRGB or Adobe RGB 1998, that only applies to JPEGs. The RAW images won’t have any color space embedded.)

There are plenty of good technical explanations available on the web and in books to prove why this is so. But to save 3,000 words, here are three screen shots from Adobe Camera Raw (ACR) that should show the benefits of working in the largest space.

The first screen shot shows an image made at sunset, with an intense orange sky. When sRGB color space (the smallest) was chosen, a large area of bright red highlight warning dominates the image. (That bright red is the highlight warning in ACR; it’s not in the image itself.)

sRGB Color Space (8-bit). (Click on image to enlarge, then click again to scroll through all three.)

When Adobe RGB 1998 color space was chosen, the area with the highlight warning was greatly reduced. This is because it is a much larger color space than sRGB. (Bit depth and color space are independent, so either 8-bit or16-bit bit depths can be used with Adobe RGB 1998 without any effect on the gamut.)

Adobe RGB 1998 (8-bit). (Click on image to enlarge, then click again to scroll through all three.)

By converting the image to the largest color space, ProPhoto, there were no pixels in the highlight warning zone, so the red warning disappeared. (ProPhoto images should be in 16-bit.)

ProPhoto Color Space (16-bit). (Click on image to enlarge, then click again to scroll through all three.)

Converting your RAW images to ProPhoto and 16-bit will give you the most data possible to work with in Photoshop.

(Just remember: When you’ve finished all your adjustments and saved your Master File, you’ll have to flatten the image, convert to sRGB, and change the image mode to 8-bits if you intend to make a JPEG. More on that to come….)

So once again, bigger is better. As far as bit depth and color space go, that is.

Best Photoshop Techniques workbook

Okay, here’s finally a link to the book you’ve heard me heartily recommend all these years. It is Charlie Cramer’s Photoshop Techniques workbook.

This is the best-written, most useful publication I’ve ever encountered regarding post-processing. Just imagine a Photoshop book that is actually fun to read, easy to understand, yet contains the essentials for getting the most out of your images. And it’s all done just using Photoshop. Don’t rely on plug-ins to make your post-processing decisions for you. Learn to use the versatile tools you’ve already paid for in Photoshop.

Not only will you learn how to optimize your image files, you will understand what you are doing and why you are doing it. You will learn to see what your images need, and how both global and local corrections can rearrange the light to more closely match the vision you had when you made the image in the field.

In addition to the magnificent workbook, Charlie includes a CD with the example images from the book with all the Layers included. Using that CD with the book will not only demonstrate the technique, but allows you to turn off the Layer, and try it for yourself, using the same image. You can then compare your version with Charlie’s. It’s an invaluable learning tool.

The workbook and CD are only $40, and are currently only available directly from Charlie. Please contact him at http://charlescramer.com/contact.html, and tell him I recommended his workbook to you. He will respond with how to make the payment. Before you know it, you will see a tremendous improvement in your images.

Make sure you check out Charlie’s work on his website at www.charlescramer.com.