Monday, March 3, 2008

Digiscoping: Post-processing - Workflow

I have modified my workflow significantly in the past few years. Once I got comfortable using Lightroom I find myself using Photoshop for only a few select modifications. If you've not used LR think of it as Adobe RAW on steroids. 

If you've purchased a new camera and shoot in RAW you've probably had to download Adobe RAW or a DNG Converter in order to open the files in Photoshop. It allows you to make adjustments in Exposure, Contrast, Highlights, etc. before actually working in Photoshop. Lightroom does the same thing. It just allows you do so much more. In fact, some people have stopped using Photoshop altogether since LR can handle all of their post-processing needs. Check out the millions of YouTube video tutorials on LR and you'll see all of its power. 

My workflow begins with transferring files from the camera to the computer. My SD cards go into a card reader while my Nikon D500's XQD cards gets read by an HDMI cable. Under the Library tab of Lightroom I select Import and copy the files in Lightroom's database. I have my settings to also convert the camera's files to DNG files, so that they can be read on any software package.

Once Imported I use the Library tab to review images and select those for deletion. You can zoom to 100% on the screen and evaluate image sharpness and feather/eye detail. Once I've selected and deleted unwanted files, its then time to Develop them. I'll start with this slightly over-exposed image to show my Develop-ing steps.

The right-hand side of the panel houses the Adjustment sliders. They are laid out fairly well. A Histogram is at the top, with Crop and Healing Tools just below. Color balance can be adjusted by moving the Temperature slider right (warmer) or left (cooler). Exposure, Contrast, Highlights, Shadows, Whites and Blacks are below that. Instead of using Contrast and Saturation tools, which adjust all colors and tones, the Clarity and Vibrance tools are valuable tools that sharpen and saturate less dominant colors. 
Sharpening and Noise Reduction tools are located farther down and do a nice job if you don't have a dedicated Noise Reduction program (I use Noiseware).
You can also activate Profile Corrections that are specific to your camera/lens. You can also select the "Remove Chromatic Aberration" tool to remove any color fringing that you might see near the edges of your photo, or along high contrast edges (white feathers).

So, I start with the Crop tool. I try to obey the "Rule of Thirds" whenever possible, instead of having my subject dead center.

Once cropped, I have a better feel for what needs adjusting in the photo. Here the stilt is overexposed as white feather detail is lost (blown highlights). Luckily, the camera has a wide dynamic range, so its possible to recover the feather detail in the image. One nit of shooting in JPG is that the dynamic range is generally less, so it might be harder to recover blown highlights (that said, JPG-Fine is still pretty good for highlight recovery these days).

I have two ways of correcting this. I can try adjusting Exposure, but to recover the blown highlights I have to darken the overall image. Therefore I'll go to option 2.

A good rule of thumb is to always move the Highlights slider all the way to the left before adjusting Exposure. This gives the best chance to recover lost highlights without darkening the overall image. You can see the feather detail in a correctly exposed image!

The next step is to make any adjustments to Shadows (move slider to right to brighten severely backlit subjects), Whites (move slider to right to brighten whites), and Blacks (move slider left to darken). I only made very slight adjustments here.

My next step is to make adjustments for noise. The image is plenty sharp, so I don't need to make any Sharpening adjustments. The Luminance slider allows for noise removal. Here I adjusted it to 50%. However, I tend to lose more feather detail when I use the tool, so I tend to make my noise reduction inside of Photoshop using my Imagenomic Noiseware Software plug-in. So, I'll move it back to zero and proceed to my export.

From here I'll export the image to Photoshop. If I right-click on the image it brings up a dialogue box that allows me to continue editing the image in Photoshop. If I don't want to do anymore editing I can select the Export button at the bottom of the dialogue (this brings up a second box that allows for additional features like adding a copyright, saving the image as a certain size, choosing filename, etc.).

This is what the image looks like so far when its transferred to Photoshop.

Photoshop has wonderful content-aware healing tools that do a wonderful job of removing spots caused by dirty sensors, or distracting features within an image. I use the Spot Healing Tool for removing small unwanted features. To remove the blade of grass in the lower right corner I just paint over the grass with the tool. You can right-click inside the image to adjust the size of the circle used to heal the image.

At this point I want to do my final Noise adjustment. As mentioned before I use Noiseware plug-in for Photoshop as it does a nice job of removing noise with less loss of detail. From the Filter menu I drop down to Imagenomic and select Noiseware. This is what the image looks like before noise reduction.
Adjusting Luminance noise reduction to 50% here effectively removes background noise and preserves more feather detail when compared to Lightroom's Luminance slider (which is still very good and used often). 

My last steps involve downsizing the image to 2048 pixels on the long side. I then perform a final sharpening of the image using Photoshop's UnSharpen tool. I typically need only Amount=50% and Radius=1.0 Pixels. I then add a signature to the image and save it as a JPG with no compression.

Here is the completed image.

Pre - 2016

Workflow Workflow is a very personal subject to photographers and it is constantly changing. My earlier workflow for processing images involved adjusting for brightness/contrast, color balance, cropping (if necessary), selective enhancement, selective cloning, sharpening and noise reduction.  I would process my subject and backgrounds differently to make the bird 'pop' more, but today's cameras are making this step more obsolete.  Here are some suggestions for improving image quality from your digiscoping camera(s):

Adjust brightness/contrast You can compensate for an underexposed image but you can’t compensate for an overexposed image. So always make sure that your images don’t contain too many blown highlights (or saturated whites). On my cameras I adjust EV to –1/3 to –1 depending upon how much white is in my bird. We can adjust brightness/contrast 2 ways: either by using the brightness/contrast sliding bars in our package, or by using ‘Curves’ adjustment. Curves is great because you can control tonal changes in brightness and contrast better than you can with just a linear adjustment. Be careful, however, to avoid blown highlights!  

Adjust color balance - 'lose the blues' By adjusting individual red, green and blue channels we can remove the overall blue cast to the image and give it a more natural color.

Crop to remove vignetting Crop that portion of the image where shadows are a problem or to place your subject using the rule of thirds. If your software doesn’t have a crop tool, highlight the portion of the image that isn’t shadowed and copy and paste into a new file.

Selective enhancement Let’s enhance those eyes a touch! When digiscoping always concentrate on the eyes. An eye in focus means your bird is in focus. In some cases, like this owl, a slight brightness/contrast adjustment to the eyes will really bring out their best feature. 

Selective cloning We’ve got a nice image to this point, but the black spots to the left of the owl and the twig to its right are a bit of distraction. We can remove those distractions with a bit of cloning. Now, before going on, let me assure you that I’m well aware of what image altering can do to the scientific validity of an image, and that its important to be aware of the science vs. art argument when it comes to things like cloning and image adjustment. As long as you let people know what you did with an image when you post it hopefully there’ll be less argument whether the image is considered real or not. Its another reason why the original digital file should never be altered… Cloning is a tool that allows the user to copy a portion of the background and paste-over or clone a bit of the foreground to remove distracting elements. You can select how big of an area you want to copy and where you want to copy it from and literally smear it over the offending twig or black spot. When used properly the final image shows no evidence of the cloning operation. Improperly used, however, the clone itself becomes a distraction.

Selective sharpening and noise reduction The CCD’s (charge-coupled devices) in compact digital cameras are quite small and prone to noise, especially under cloudy conditions and at higher ISO settings. Thus, noise reduction is an important part of every image package. There are several software packages available dedicated solely to noise reduction and have received favorable reviews by users: Imagenomic Noiseware 2.5 and Noise Ninja. If you don’t have software package available, you can apply selective smoothing or blurring to images to remove noise. In Photoshop this would be termed Gaussian Blur. My workflow for noise removal is the following: - highlight subject, apply light blur followed by sharpening - highlight background, apply more blur Photoshop has a ‘magnetic lasso’ tool that allows you to freehand draw a line that will snap to the nearest sharp edge (bird’s body). A line 1-pixel thick will allow you to highlight the bird or part of the image of interest. Then apply a Gaussian blur (or smoothing) to the highlighted subject (I use 0.5 pixel) to remove some of the pixel-effect before applying any sharpening. Otherwise, sharpening will only increase the amount of noise in the highlighted subject. Now apply a sharpening filter to bring a bit of snap to the subject (in Photoshop I use the Unsharpen Filter – Amount=75%, Radius=3.0 pixel, and Threshold=0) that allows a bit more control over the amount of sharpening to the image. Avoid too much sharpening – this leads to higher contrast that leads to loss of detail, more noise, and even a halo-effect that looks un-natural. To process the background, Photoshop has a Select\Inverse function that will now highlight everything ‘except’ the subject. Now we can apply a bit more Gaussian blur or smoothing to give more noise removal to the background. And that’s it! Here is our image before and after post-processing.


A note about color fringing We talked about chromatic aberration in scopes and in camera lenses. We can remove some of that purple halo around the bird by de-saturating the ‘blue’ color channel. In Photoshop select \Image\Adjust\Hue/Saturation and de-saturate the color blue until the halo disappears. This will also give the image a more natural color overall.

Add a copyright symbol? – [Alt][0169] = © A copyright symbol added to a web-posted image will not prevent others from stealing your images, but it will make it more difficult for someone to take credit for your work. Use the number keypad on the right side of the keyboard to make a copyright symbol. Hold down the [Alt] key and type 0169 on the right keypad and release the [Alt] key.


Dale Forbes said...

this is another great blog post - seems I missed it last year when you originally posted it. it certainly pays to come by here every now and again and wander about to see what I can see...

Nelson said...

Jerry- I understand your presentation- however, the more you digiscpoe, or even spend most of your time birding observing through binos, or a scope, the more you are setting limits on what is out there to be observed.
I am talking specifically of hawk watching. You will never understand that Northern goshawks are moving into cities and suburbs, and have been doing so for many years. This raptor is usually always observed in the sky, and very seldom perched, is one of the most exciting raptors to observe.I have 16 years of continuous observations of goshawks while living in Southern CA, Coastal Washington, many areas of East Texas, and many areas of Southern AZ. I will try and adapt my scope and camera to a shoulder stock and try and garner some verification photos of Northern goshawks. Nelson Briefer - Goshawk specialist- Tucson and Anacortes, WA.