Category Archives: Hot or Dead Pixels

The 5 Most Used Photo Enhancement Techniques – Part 3

Out Darn Spots – Cropping

Beware cropping too soon. It is an easy way to get rid of problematic areas of the frame, but might bite back!

One obvious way to remove encumbrances is to crop them out. As tempting as it seems to crop the photo first, we generally leave cropping to the end of the effort for several reasons which we enumerate here:

  1. Sometimes clients (i.e. you) want an image in a different format. Instead of 14×11 you may want it in 20×16. If we crop it first, we are deciding the display format without thinking it through. Sometimes the ratio will be obvious due to the subject, but usually there is some room to play. We prefer to keep our options open until the end.
  2. By cropping out edges, we may be throwing away good sources for cloning out defects, or making cloning and healing harder because operations at the edge of the frame are not as neat.
  3. Care should be taken to not have details at the edge of the frame. What happens, for example, if you are asked to make a canvas wrap of your image (in our Half Dome example, the hiker would be perilously wrapped at the edge).
  4. More than once we have discovered that a portrait mode image worked better in landscape and vice-versa.

It IS true that if we do not crop early we may end up wasting effort on portions of the image we ultimately will discard. Sometimes it is obvious that a portion of the image is unusable and will be cropped. Once we cropped out two figures at the summit of Half Dome to focus attention on the landscape. We later discovered that a tiny figure at the edge of the scene provided both scale and human interest. The California Wine Institute probably would not have been interested in the person-less scene.

Dawn sky atop Half Dome [9753]

Closely related to the cropping problem, is the compositional decision when the photo is taken. We have learned the hard way that its good to leave room around the edges of the frame – one never knows how much space will be needed after cropping to a specific size.

We will not spend much time on cropping, except to restate our premise that cropping is something you should NOT do until you are ready to print or display your image. Secondly, you will find it advantageous to crop in a STANDARD ratio if you expect to frame or mount your images.

In Lightroom, the crop tool is found just to the left of the Spot Healing tool (see below). In both Lightroom and Photoshop the crop tool is overloaded. It can crop, rotate and straighten (and in Photoshop the crop tool also resizes!). Perhaps the best advice we have is to use a pre-set Aspect ratio. You can also add your own ratio(s).

LR_Croptool

Our next bit of advice with respect to cropping: in Photoshop we do not recommend cropping and resizing as one operation. Crop using a “ratio” and only later should you resize, that is, keep as much of the image intact as possible for as long as possible.

Our last bit of advice on cropping: if you DO crop an image in Photoshop, when you save it, include the image pixel dimensions.  Nothing is quite as frustrating as saving a cropped image and destroying the original! Our practice is to always save cropped images in a subfolder named “Exported”.

We could conduct a diatribe about “DPI” and “PPI” and explain why those are pretty useless things in most contexts, but we will not!

Healing Out Dust Spots, Hot Spots and Unwanted Things

Perhaps one of the easiest tools to use in Lightroom (and Photoshop) is the Clone/Healing tool. Unfortunately, you need Lightroom 5 to get the features shown here.

LR_CloneHealTool

The “Spot Removal Tool” in Lightroom can Clone or Heal

Most of the time you will want to HEAL rather than clone.  Clone, as it sounds makes a copy of the source over the destination.  To heal or clone you click the spot healing tool, adjust the size and then click the area of the image with the problem. Lightroom will select what it thinks is a similar area from somewhere else in the photo. You can drag the “similar area” selection somewhere else if the selected area does not make sense (such as picking a fence to replace a grassy spot).  Generally it is best to make the brush only as large as needed. If a line is to be healed out clicking and dragging often works.

Heal out A Satellite Streak in Lightroom

Heal out A Satellite Streak in Lightroom

After dragging along the unwanted satellite trail in the photo above, Lightroom finds a matching area of the sky. In this case the area Lightroom chose will duplicate stars, so we drag the handle of the chosen area to a blank sky.  Note that the blob at the upper left indicates the area used to heal the area at the end of the white arrow.

Heal a segment, Lightroom

Heal a segment, Lightroom

Done Healing

After dragging the source area click Done to complete the healing

And when done, click “Done”. If the healing looks bad, you can delete and try again. Healing out spots in Lightroom is a little more tedious than doing so in Photoshop in part because having overlapping healing areas is difficult in Lightroom. (The only way to overlap healing/spot correct areas in Lightroom is to create a new spot and drag the source and destinations so they overlap a previous heal.  In Photoshop, we strongly recommend creating a separate layer to do healing on – but wait until near the end of your processing to do so!  The easiest way to create the layer to heal on is with the magic key sequence Control-Alt-Shift-E  (Command-Option-Shift-E on the Mac). That key sequence effectively does a “merge visible layers” but creates a new layer as a result.  If there is only one layer use Control-J (Command-J) instead.

Healing In Photoshop

Photoshop Spot Healing Tool

Photoshop Spot Healing Tool

There are MANY tools for “healing” in Photoshop.  There are also two flavors of the “Clone” stamp tool found under a separate palette. To choose the spot healing tool, click J (Shift-j) until it looks like a bandage with a dotted selection behind it.  You can also right-click the tool and select as shown above.  If you use the OTHER version of the bandage (healing tool) you must first select the area to use as the source using alt-click (Option-click on a Mac). In our experience it is seldom necessary to select the source so that extra step is wasted effort.  To heal in a straight line in Photoshop, click the first location then hold down the shift key and click the second region.  The shift-key trick works for most Photoshop operations like brush strokes, too. The shift trick does not work in Lightroom 5.2

There are some settings for the healing tool so if things get weird, double-check the tool bar at the top – make sure it is Normal mode.

Photoshop (CC) Healing Tool Settings

Photoshop (CC) Spot Healing Tool Settings

As a final step we regularly “heal” out hot pixels from our final night image. The Photoshop spot healing tool is very easy to use even if there are a hundred spots to fix. While it might be tempting to rely on noise reduction to solve the hot pixel problem, significant blurring occurs.

If you have a particularly difficult healing problem there are yet more advanced techniques, for example you can use the Clone or the Patch tool. Generally you will use the healing tool when you want to make the area being fixed look like the rest of the image and you will use the clone tool when you need to duplicate a texture or remove a larger hindrance.  For example I found it was easier to clone out the glowing orange highway safety cone that someone (or something) had cast into the brush just above where my name is in the image below.

Dream Highway [C_071601]

 

If there is interest we can cover how we handled a severely over exposed area in this image by using the patch healing tool.

The area at the left was over exposed so I used the "bump" rock in the right hand third to fix it. This is "rough"

The area at the left was over exposed so I used the boulder in the right hand third to fix it. This is “rough”

Looking for the prior two articles? Check Part 1 and Part 2.

Advanced Stacker Plus – It’s HERE!

We are always tinkering with our products here at StarCircleAcademy to make them faster, more powerful, and able to leap tall buildings in a single bound. We have overhauled the StarCircleAcademy Advanced Stacking Action.  Here are some of the things we did:

  • Split the features into clearly identifiable sets of operations.
  • Added automation for the “Bump Up” and “Pump Up” star effects (the Pump up technique has been discussed in the NP150d webinar and is also called the Dust-Subtract StarMask).
  • Added the ability to resize, watermark and save both individual files and intermediate files used for creating a timelapse
  • Included custom resizing and watermarking of your images – individually or in batches.
  • Fixed a bug here and there:
    1. Some operations didn’t preserve the ProPhoto color space – they now do.
    2. The All-in-One darken operation was confusing people so the effect has been scaled back by default.
    3. Fixed a problem that prevented proper operation on PS CS3
  • Created a Starter Set (TEST Stacker) that behaves much like Advanced Stacker+ so you can try before you buy.
  • CropAreaProblemExpanded the instructions, added more help in the actions, and included troubleshooting to help with errors you may create using the customization features.

While actions are not the most powerful method for performing operations, they are by far the most portable and the easiest to install and get running.  Simply download, unzip and click (or drag and drop) to install.

StarCircleAcademy Advanced Stacker PLUS Download and Install Instructions.

How do you find, buy and install the StarCircleAcademy stacking action? Watch above and find out.

If you already have it installed, move on to general usage instructions here.

Take a look here for more advanced operation, including using Intermediates and customizing the output.

SCA_AdvancedPlusMenu

There is awesome incredible power in this itty-bitty living space. The first thing that is obviously different is that the Stacking Action has been segregated into four Action sets:

  • StarCircleAcademy Stacker Advanced
  • StarCircleAcademy All in One
  • StarCircleStacker Customizations
  • StarCircleAcademy Primitives

The features found in the Advanced Stacker are visible in the “Stacker Advanced” and “All in One” sets.

The Primitives are the basic building blocks of the family of operations and should not be used directly.

The Customization set is for you to adjust how you want the actions to behave. You can create your own watermark, align the watermark how you like (upper left, bottom right, middle, etc.), custom crop or resize your image(s) and pick what kind of file to save when a file is written.  Choices are as easy as clicking!

New Features

PumpUpExample

Two methods of brightening stars have been added to the Advanced Stacker+ Those methods are the Bump Up technique and the Punch Up technique (which I sometimes call the Pump Up). The Bump Up has been well described here in the BLOG, while the Pump Up is an action to implement a method I’ve taught in the Night Photography 150 Photo Manipulation Webinars.  The Pump Up technique can be automatically applied to each frame of a timelapse or applied to any single image with a click. You can see how much the stars have been enhanced from the original image above – there is such a thing as too much!

A Batch Resize and Watermark operation has also been added. You can use the action as a batch command or on a single file. Your file is loaded, custom sizing, and watermark are applied and file the is saved using your pre-chosen file type and quality. And there are some simple operations you can quickly apply like resize to 1000 pixels high, or HD format.

If you purchased the Advanced Stacking Action, or the Bundle including the Advanced Stacking Action, you can upgrade to Advanced Stacker+ for free, we’ll send it to our registered users.  If you don’t already have one of our stacking actions here is a helpful hint: watch the video above!

Latest Changes

  • August, 2013: Version 13B Numerous little bug fixes, plus we added an (undocumented as yet) feature to load watermarks. Very useful for preparing files for web or social media.

More to Come

We have not run out of ideas, but it takes a bit of work to create and test all of the actions and combinations on all the possible Photoshop versions we support – not to mention documenting and providing clear examples.  Just know that we have some spectacular plans ahead as well. With the core operations in Advanced Stacker+ you’ll have the building blocks for even more advanced tools.

And Yet More

We’ll also be inviting owners to free Usage Clinic webinars from time to time where we’ll help you work through using the Advanced Stacker+.  Express your interest on our Subscription page by selecting “Usage Clinic”.  NOTE: You must already be subscribed to see the Usage Clinic option.

Star Trail Creation – Step By Step

Originally Published: November 19, 2012
Last Revised: March 3, 2017

I dredged this one up out of the archives. Many people ask me “how do you do those star trails, Steven.”  If you want a grand overview of the process, my Treatise on Star Trails is a good read. However here I reveal step-by-step how I create a star trail image from the first shots to the finished image. The method shown below is for creating simple (lighten mode) star trails. If you want to do some fancy effects, please take a look at our Advanced Stacker Plus.

Here we go.

South Side [C_009842-75br]

Photo 1: Quickly stacked image which is a composite of thirty-three 6-minute 500 ISO exposures and one 30 second, ISO 2000 exposure.

The above is my first quick attempt at creating a star trail, and following is summary of how I created it.

It starts with the test image and continues with the exposure set. For background on how to navigate the various shooting choices, see: the summary Stacker’s Checklist. The theory about selecting exposures may help.  And there is a two-part series that addresses the difficulties you may encounter. See Part 1 and Part 2. If you’re curious how I get the stars to form circles, this article will provide the information.

I usually start with a short (30 second or less), high ISO exposure to gauge several things: 1. How well framed my subject is, 2. How sharp the focus is, and 3. What I may need to adjust to control the sky-glow.

Photo 2: First, image: ISO 2000, f/2.8, 30 seconds.

After taking the first image, I realized two things: one is that the trucks passing were providing helpful light on my foreground – but not always illuminating the entire thing.  The other is that the exposure (ISO 2000, f/2.8, 30 seconds) was under exposed.  I needed to at least double the exposure to 1 minute. Let me stop for a moment. Those of you who don’t do much night photography are thinking “Whoa from 30 seconds to 1 minute is a huge difference.”  But no, it’s not. It’s only one f-stop. It is no different from changing a daylight exposure from 1/200 of a second to 1/100 of a second.

Starting with an exposure at 1 minute, 2000 ISO f/2.8 as a starting point I calculated an  ISO 500, 6 minute exposures at f/3.5. Here is how: A 1 minute exposure at ISO 2000 is equivalent to a 4 minute exposure at ISO 500 (500 is 1/4 of 2000).  Changing the aperture from f/2.8 to f/3.5 drops the light by about 33%, so I increased the exposure from 4 to 6 minutes.

I set my camera to record in RAW and my interval timer to take 5 minute, 59 second exposures every 6 minutes. I pulled out my reclining beach chair, a sleeping bag and slept while the camera clicked.  Below are a few of the shots. Note how the light changes from passing trucks!  You can also see the counter-clockwise rotation of the Milky Way. The last shot was taken as twilight approached is too bright to use because the sky is losing contrast and the light on the cliff is looking flat. I did not include that last shot in the stack.

Photo 3: Collage of some of the photos used in the stack.

I downloaded all the images from my card to my Incoming folder which is organized by date.  I used Digital Photo Professional to pull up the images, applied a bit of contrast enhancement, a slight exposure increase (1/3 of an f-stop), and a very slight noise control over the entire image. I exported in Landscape style which adds a slight saturation increase (Photoshop Saturation and Vividness) and modest sharpening. I cloned the recipe to all the photos and exported them into a “RedRockEast” folder in a temporary directory.  I could have done all these things with ACR (Adobe Camera Raw) or Lightroom.  In this case I didn’t have to do any white balance adjustments because I had preset the camera to approximately 4100K.

I then dragged and dropped all the exported (JPG) images onto Image Stacker which took about 3 seconds per image – less than two minutes to create a result. My option for Image Stacker was “Brighten” mode. I could have used the Star Circle Academy Stacking Action in Photoshop instead and the result would have been identical.  The stacking action takes about the same amount of time, but is more versatile and can even use raw images. (Note: StarStax is a program that supports Mac, Unix and Windows and works well, too!)

Photo 4: First Results stacking 34 images in Image Stacker by Tawbaware – this is effectively a 3 hour, 24 minute exposure.

The result was a little dark and flat so I used Picasa 3 to increase the exposure (called Fill Light), highlights and shadows – each by about 1/4 of the scale, and I warmed the photo by slightly tweaking the white balance (Color Temperature). That was all I needed to get the image shown in Photo 1.

Screen Shot 1: Picasa Adjustments

One obvious problem with the result is that the combination of the early short exposure with the sequence of shots left a gap. There really was no reason to include the first shot.

I want the cliff to pop a bit better, so my next course of action was to work on improving the foreground.  I found all the brightest shots of the cliff face (e.g. when the trucks were lighting them), and combined them using additive stacking to brighten them and averaging to reduce the noise. Remember that “brighten mode” (Lighten in Photoshop) does not brighten anything – what it actually does is select the brightest pixels at each location from each of the images in the stack.  The brightest pixels may also be noise! Using averaging reduces the noise significantly – but it will not remove “hot” pixels; we will address those later.  Fortunately Image Stacker has an option to stack and average. All you need do is specify the divisor.  If you have 10 images and specify a divisor of 10 then you are simply averaging. But if you specify a divisor of, say 5, then you are averaging AND effectively increasing the brightness by about 1 stop.  I used 12 images and a divisor of 3. And I made the same adjustment to the result in Picasa as I showed in Screen Shot 1. But I wasn’t happy with the result – the foreground still wasn’t bright enough.

Next I took 10 of the brightest images and Stacked them (additive).  After tweaking shadows and brightness in Picasa I got this:

Photo 4: Additive stack of 10 images.

Now my foreground is better, but I have created a new problem. The sky is over-bright and the hot pixels and the noise are significant as shown in a 100% crop below.

Screen Shot 2: 100% view showing Hot Pixels and noise (white speckles)

The hot pixels here have a purple fringe to them. Sometimes hot pixels are tinged red, green, blue, white or gray. I will fix hot pixels in my next to last step using the clone stamp (Picasa’s retouch) or the healing brush in Photoshop.

While the noise is obvious at 100% I think it will be fine so I am not going to address it.  If I later find the noise intolerable I will go back and stack more images and average them. Or I may return to the original images and apply stronger noise reduction in Digital Photo Professional and re-export them.

My next task is to remove the over-bright sky from the Photo 4, above. Sky removal is rather easy with the wand selection tool in Photoshop. I select all the sky and fill with black after making a few more tweaks to contrast and color.

Photo 5: Sky removed and replaced with black.

Since I now have a black sky version with the foreground as I like it, I can include this frame in any other stacks I make, and my foreground will be just as I want it. If I were working entirely in Photoshop, I would not have to fill with black, I could just use the result as a layer with only the foreground revealed by a mask.

To complete the process, I restacked 33 images together with the sky-less foreground image (Photo 5). Some more minor shadow and color temperature tweaks and some spot corrections of the few hot pixels (there were about 15), an addition of my copyright and this is the result:

Photo 6: Final Image

Since I had all the images for the stack, I was challenged on Flickr to also make a time-lapse video. This video below also helps to illustrate how stacking works. I collected the original thirty-three 6 minute exposures and cropped them to HD format (1920 x 1080). I then created and a sequence of stacked images using the intermediates option of Star Circle Academy Stacking action and joined them into an animation complete with a lovely snippet of the song Kidstuff by Acoustic Alchemy. In my next column, I’ll show how to create the time-lapse animation.

Red Rock Dancing *Explored 03-03-2011*

If you would like hands on experience and instruction, you can join us at a StarCircleAcademy Workshop

Advanced Star Trail Tricks

Published: Oct 11, 2012
Last Update: February 14, 2018 (remove Flash)

I have been playing with Star Trail processing for quite a while.  Ever since I wrote the StarCircleAcademy Stacking Action I’ve been tweaking processing to try different things. Sometimes failure is inevitable, sometimes… well, you’ll see.

First, you may want to look back through my earlier columns on shooting and processing star trails because this is not a primer on star trails – it builds on what I’ve previously written and this is not a good place to try to understand what stacking is.

Second, please understand that I use a variety of tools but almost all of my more successful endeavors end up as layers that are combined in Photoshop (CS5 at the moment).  You could combine your layers in GIMP if you don’t have Photoshop, but you’ll be out of luck if you try to use Lightroom.

Here are my star trail effects:

  1. Smoothee – Averaged sky and/or foreground to reduce the grittiness that sometimes results from brighten stacks. I’ve been espousing this for quite a while. See the Simple Astrophotography Processing Technique.
  2. Blobulous – stars at the beginning (or end) of a trail are made to stand out from the rest of the trail.
  3. Comets – star trails appear to grow brighter and the end of the trail looks like the nucleus of a comet.
  4. Streakers – Like comet only the trails are longer
  5. Blackened – A clever trick removes sky glow from light pollution, the moon, or twilight.

And of course you can make “Blobulous Comets” and “Blobulous Streakers” and “Blackened Smoothee Comets” and more.

Building Blocks

To creatively combine exposures, I usually create the following stacked frames.

  • Dark (Darken in Image Stacker/StarStax)
    The darkest elements emerge – especially the hot pixels
  • Brighten (aka lighten) stack
    The Brightest of everything is present, including hot pixel and more noticeable noise
  • Average
    Contrast is reduced, smoothness increased.
  • Additive (called “Stack” in Image Stacker)
    Hot pixels become really bright.
  • Scaled (called Stack/Average in Image Stacker)
    Allows some increase in brightness but more smoothness, too. Experiment with different divisors.

Normally I create all of these combinations using Image Stacker against my JPG files because it is really easy to do.  I end up with a set of frames something like these although I’ve significantly brightened them so that they are easier to see.

Smoothee

In a Nutshell: Combine the Average stack over the Brighten stack using Normal mode at 45% opacity.

I’ll start with the Smoothee technique since it’s probably the easiest to do and perhaps the easiest to understand.  The problem with “Brightness” (or lighten as it’s called in Photoshop) is that it will also pick up all the hot pixels, and the brightest bits of noise.  Averaging on the other hand tends to smooth out everything except for truly hot pixels since most noise is random. By putting an averaged stack as a layer over the brighten stack and then adjusting the blending modes and opacity you get a smoother sky and foreground.  Exactly what settings to use depend on the images, but surprisingly many of the blending modes for the Average layer work here including Darken, Multiply, Overlay, and Normal. The starting place for Opacity is about 45%.

Hint: You can also use an Additive stack instead of the average stack but usually only the Normal blend mode will work.  For even more fun combine the Additive stack and the Average stack.

For additional smoothness you can also subtract the “Darken Stack” while adjusting the opacity to prevent halos and weirdness.

Blobulous

In a Nutshell: Add one of the single frames more than once.

What do “Blobs” look like? Like this…

“Fat Star” processing.

There are two ways to produce “Blobs”. One way is to add “Comets” to a smoothed star trail. The other is to simply pick an image (usually the last one in the set) and add it in using “Add” or “Screen” mode. To make the blob more pronounced duplicate the last frame so it’s added twice. BUT remember when you add in any single image the hot pixels are going to come out… and even more so if you add an image twice.

Comets and Streakers

These two techniques require some fancy stacking techniques. Fortunately I’ve created an action to do all the fancy stuff.  I’ll be rolling out the action and the explanation to my Photo Manipulation Webinar participants first <NOTE: The Advanced Stacker PLUS action has been released and is available for purchase in our store>.

Oh, here is a peak at what the Comet action looks like:

What's The Point?

And here is what an animation of comets might look like:

Star Rise

 

Settings

I know you’re going to ask so let me save you some typing. Except for the “Comet” image above, all images used in these illustrations were taken during the Ancient Bristlecone Pine Workshop in the Patriarch Grove on White Mountain, East of Bishop, California.

The 34 or so images that I’ve combined in the examples above were all taken with the following settings: Canon 50D, ISO 400, f/3.5, 79 seconds, 10-22mm lens at 15mm.