Category Archives: Photoshop

Trimming away the Excess (Photoshop)

I created a problem for myself twice and with the Total Lunar Eclipse coming in April, 2014 I suspect I’ll be creating the same problem again.  I wanted to record a time-lapse of the May 20, 2012 Annular Solar Eclipse as well as the June 5, 2012 Transit of Venus.  I used a solar filter and an Equatorial Mount to help me track the sun. Unfortunately getting a good polar alignment during daylight is beyond my skill set. Without good alignment I had to manually repoint the telescope rather frequently. It is not necessary to understand any of the gobbledygook you just read except to know that the sun was MOVING from frame to frame – see the image below.  With all that movement, a time-lapse looks like a jitterbug dance.  In fact, this artsy composite shows just how much the sun moved around in my frame – that is, all over!

Solar Art

Annular Solar Eclipse with un-centered and trimmed frames. AKA Solar Art the “dots” on the sun are large sunspots.

My friends suffered from similar problems and each of them undertook automated solutions to the problem using Photoshop or something similar.  My goal was to solve the problem in a generic way and along the way I learned some useful additional Photoshop tricks.

The Solution

I used the trim feature of Photoshop.  You can find Trim under Image -> Trim.

Trim makes note of the current value of the upper left (or lower right) pixel. It then creates a selection that includes all of the rows and columns that have the same value and inverts the selection. Finally it crops off all of the selected area into the smallest possible rectangle.

An easy way to think of this is: imagine a dark photo with a white frame around it.  By using “trim” the entire white frame will be cut away.  The same approach works if the frame border is black, blue, transparent, and so on.

But there is a catch!  There is no tolerance setting for the trim value so whatever needs to be trimmed must be an exact color match. Unfortunately this presents a problem because even in a photo of a black sky, the black areas are not uniformly black.  Some values may be 0,0,0 but others 1,2,1.  And then there is noise!  Even though you may not notice a difference between two adjacent pixels trim only operates on those pixels that have EXACTLY the same value as the upper left or lower right.

To get trim to work in a reasonable fashion, therefore, we must turn all of the almost black pixels into black (or some other color).  I feel a Photoshop trick coming on here. Our trick is to use a duplicate layer and adjust it to cause it to trim the way we want. We will discard the duplicated layer when we are done.

Trim-o-Matic

  1. Open the image.
  2. Duplicate the image as a new layer.
  3. If the duplicate layer is a smart object, convert it to a raster layer. (To convert a smart object to a Rasterized Layer, open the layer palette, right-click on the duplicate layer and select “Rasterize Layer”)
  4. On the duplicate layer use
    “Filter -> Noise -> Dust and Scratches” with Radius = 3 and Threshold = 3.
  5. Make sure your foreground color is black (x is the hot key).
  6. Use the “Fill” tool (paint bucket) with tolerance set to 40, Opacity 100%, Mode = Normal and no options checked.  Click the extreme upper left pixel. Fill will replace all of the outer area with black. You may want to click multiple times.
  7. If you have some areas that are brighter than the object, you may also want to apply a brightness and contrast adjustment.
  8. Use the trim function on the current layer with all boxes checked and “Top Left Pixel Color” selected.
  9. Trimming changes both the working layer and the original layer below it.
  10. Discard the working layer.

Here are the steps in illustrations.

Rasterizing a smart object

Rasterizing a smart object

PS_DustAndScratches

Dust and Scratches settings

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Filling with black

Filling with black (might need to repeat this)

Dust and Scratches + Fill may not be enough. Fortunately the duplicate layer can be severely adjusted if needed since it will be discarded.

 

Trimming Tool

Trimming Tool

Select Areas for Trimming

Select Areas for Trimming

 

After Trimming

After Trimming

Delete the Extra Layer

Delete the layer that was created for the sole purpose of trimming

 

What If It Crops Too Tightly or Inconsistently?

This set of steps written as an action can be used to automate the process of trimming. There are still a few remaining problems to work out. Sometimes after trimming the total horizontal or vertical pixels of the object the resulting image size will differ by one or two pixels. To solve the “dimension” problem, the simplest method is to use Image -> Canvas Size. Set the canvas to about 20 pixels larger in each direction. Select “center” (the dot in the middle next to anchor) and set the fill color to match the background.

Expand the canvas and center the image

Expand the canvas and center the trimmed image

After Trim and Canvas Size

After Trim and Canvas Size

The above procedure will work quite well for animating a sequence of sun or moon shots – except for eclipses.  Eclipses don’t work properly because an edge of the sun or moon disappears leaving no edge to properly orient with the others.

What can we do when we no longer have constant edges to align with?  Divide and conquer! Instead of trying to apply the same action to all of the images, we will can change edge we select when enlarging the canvas size. We can orient sets of images based on which part of the image remains constant.   Which edge or corner should you pick? Pick the edge that stays the same (if there is one!)  For an Annular solar eclipse, at least one of the directions will never be darkened – that’s the one to pick!  The annular eclipse sequence shows that the upper left limb and lower right limbs of the sun remain present in all of the shots.

Field Rotation

There may still be another problem: Field Rotation. If you’re thinking that perhaps this has something to do with improving crop yields on a farm, sorry to disappoint you. The Annular Solar Eclipse and the Transit of Venus were events that took place over a period of from 3 to 5 hours.  During that period the earths rotation causes the sun, moon and stars to move. It also causes them to “turn” as viewed from terra firma.  You can see this for yourself if you watch the full moon from moonrise to moonset. At moonrise make note of the orientation of the “man on the moon” and compare it with the orientation at moonset. Go ahead and watch. I’ll wait for you.

So what do you do if you have this field rotation?  Either live with it and accept that the animation won’t be entirely accurate, or you’ll have to do a much more complicated set of operations by progressively rotating the images.  That’s more than we want to tackle, so you’re on your own for that!

The Results

The Annular solar eclipse sequence. The Abstract Solar Art image at the top of this article was created from the un-centered and trimmed frames. Obviously this wasn’t perfect – in part due to clouds and shimmer in the atmosphere.

Not seeing the above video? It requires FLASH, so click here to watch.

Obviously this one had some trimming errors… and nasty dust on the sensor but this is the once in a lifetime Transit of Venus.
Not seeing the above video? It requires FLASH, so click here to watch.

Doing things Backward in Advanced Stacker PLUS

Push Me - Pull You

Star Trails tapered in TWO directions… read on for how.

First we confess… Doing things backward applies to all manner of operations, not just Advanced Stacker PLUS so this technique is useful for almost any kind of batch processing.

By far the most IMPRACTICAL way to stack your shots in reverse order is to reverse time before taking your shots so that they will be numbered as you wish. Another eminently impractical way to shoot star trails backwards is to reverse the earth’s rotation before shooting that sequence of shots. 🙂

We’re pretty sure you are looking for a more practical solution, though! And here we offer a strategy that takes full advantage of Photoshop’s relentless bent on processing photos in alphabetical order.  To make everything run “backward” we need to reverse the alphabetical order of the photos.  Unfortunately, there is no number these files backward feature. We wish! There are some standalone programs for doing sophisticated file renaming but here we will use a tool you already have: Adobe Bridge. Adobe Lightroom can be used too – if you are anxious to know how, leave a comment and we will elaborate.

Here is a quick comparison. The first shot is “reversed” causing the stars in the Northern Hemisphere to be rotating clockwise instead of the counter-clockwise direction that they ACTUALLY move in.  While exactly the same shots were used in each case, the photos reveal one reason why you might want to reverse the order – to get a sky flavored with a bit of twilight blue.

130-41ReversedComet 130-41Comet

We have a lengthy article on how to use Adobe Bridge to feed the Advanced Stacker PLUS, so let’s start with using Bridge.  Below is what our directory of files looks like. We compacted our Bridge display to make it easy to get a reasonable size screen capture. We slid the  leftmost divider (normally it shows filters and folders) to the left.  Notice the “content” pane contains thumbnails and the Preview pane shows the two files we selected – one obviously taken earlier when there was yet some blue twilight, and the other taken later.

Reversing the File Order – Adobe Bridge

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Arrows below indicate places where we can control the view that Bridge shows us.

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Some key controls for manipulating the Bridge display are shown.

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NOTE: You do not have to change the view, you can use the Sort option and uncheck the “Ascending” order.

We find that the easiest way to reverse the displayed order is to change to List view. And then click on the header to reverse the sort order. While we can change the sort order directly (see sidebar) we prefer the neater view we get in List mode.

Clicking the triangle on the Name column at the top of our content pane reverses the sort order and results in the display as shown at the right.

gs_2014-02-26_081642gs_2014-02-26_083730

Unfortunately Photoshop will not be swayed by the different sort order… it insists on processing files in ALPHABETICAL order. Our solution is to change the names of our files to reflect the desired ordering.

Batch Rename

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Batch rename (under Tools) gives us the ability to copy or move files while renaming them.  Fortunately when we use the rename tool, it DOES respect our sort order. Our strategy is to use our reversed-order file list and place an increasing sequence number at the beginning of each file name. By prepending to the file name we can force the first file in our sorted list to become first alphabetically.  Bridge has a built in “Sequence Number” which automatically increments.

We do this often enough that we took the extra step to save the configuration as a preset.

gs_2014-02-26_082508
Adding a 3-digit prefix followed by a dash character. To add or remove items from the rename click the + or – icons.

The important points are:

  1. We must prefix a sequence number.
  2. We strongly suggest “Preserving the current file name in the XMP data” so we can return the files to the original name if we wish.  Or instead of renaming them, select “copy” and place the result in a separate folder.

Once we have our renumbered files, we can feed them to Photoshop just as we described in the Stacking with Bridge article.  And, if use the “preserve file name in XMP” option, we can easily rename the files back to their original names using the batch rename. The small trick for this is described at the end of the video below.

Batch Renaming – The Video

Reversing the ordering of files for Advanced Stacker PLUS (Using Adobe Bridge)

 

Using Lightroom To Rename

Using Lightroom has many drawbacks as we previously described.  Lightroom also has a rename function (F2), it is, however a bit more tedious to set up.  The other important thing to remember about using Lightroom for stacking is that Lightroom insists on exporting files before you are able to stack them.  And because of these two complexities, we decided to stop writing here.  If you really want to know how to use Lightroom to accomplish the same task, plead with us in the comments below.  Or better yet, offer us bribes!

The 5 Most Used Photo Enhancement Techniques – Part 2

You are back! Good. In the last article we talked about White Balance and Noise Reduction. As two of the five most useful tools in the arsenal of the night photographer.

In this article we will tackle two of the remaining items:

  • Exposure and Contrast enhancement
  • Sharpening (and de-sharpening)

Healing and cloning will be in Part 3.

While we have seem some fascinating composite and highly edited images our goal is usually to make a compelling photo. But we do like realism, too. So while we will show techniques that can be pushed to extremes to make gaudy Milky Ways, or super saturated star trails, we personally do not go there often.

Exposure and Contrast Enhancement

Below is the result we want to achieve.

640_4

Single Exposure with exposure and contrast adjustments, healing, cloning, selective blurring and sharpening.

But we will be starting with a single daylight exposure from the Outer Banks, North Carolina. When we shot the scene we shot a bracketed exposure at one-stop intervals. Before we look at the exposures, let’s look at the histograms from each of the three exposures

RodantheHistograms

Which one is the best image to start with to make our adjustments? Hint, it’s the one at the right. The +1 exposure has no loss of detail because nothing has been over exposed.  Here is the exposure.

+1 Exposure

+1 Exposure

The scene seems flat and lifeless – almost nothing like it looked to the eye, and not close to what we hope it will be. Part of the reason it looks so flat is that we have not done any adjustments to the original RAW file. If you shoot JPGs the curves and saturation adjustments are automatically applied so you might conclude that RAW images are a waste of time. That would be wrong. The truth is there is much room for improvement in the RAW images and much of the “good stuff” is lost when the camera applies the conversion to JPEG.

All of the histograms show decently exposed images. But it looks like even in the +1 image we still have some room left. That is, we could have exposed a bit more to get the whites all the way to the right.  All of our histograms show that we have no black (nothing at the left edge), and no white (content at the right edge).  An underexposed image might have richer color but it will suffer when we boost the exposure and contrast. The lighter exposure will suffer much less degradation. In fact, the act of reducing exposure deepens the saturation – we do not have to play with the saturation sliders at all!  Pleasing saturation shifts from adjusting exposure are one of the many good reasons why exposing to the right (ETTR) is an effective strategy.

Adjusting Exposure and Contrast – Lightroom Auto

There are many ways to adjust contrast and surprisingly the “Contrast” slider is not usually the most effective way. Using contrast alone often makes the lights too light and the darks too dark. One thing you can try is to use the “Auto” button. It sometimes works. In fact, for these images, it works pretty well with the +1 exposure, but not as well with the normal exposure.

The "Auto" feature of Lightroom under Basic settings

The “Auto” feature of Lightroom under Basic settings

Here is what Auto did for this image:

Lightroom Auto Adjustment

Lightroom Auto Adjustment

The histogram has been stretched and the image looks pretty good. Note that we’ve turned on the clipping indicators by clicking where the white arrows point. After Auto we found a few small spots where black level clipping has occurred as indicated by blue blobs which are circled in red above. No big deal. You can also see what Basic adjustments Lightroom made – exposure has been reduced by one stop, contrast +20, whites +62, blacks -50.  We now have an idea what the Basic adjustments can do. Auto almost never creates a good result when working with dark or night images.

Adjusting Exposure and Contrast – Lightroom Tone Curve

There is another way, and in our opinion, a more powerful way to adjust the exposure and contrast and that is using the Tone Curve. One reason we prefer this method is that it has an almost exact analog in Photoshop (Curves), as well as an almost identical behavior if using Adobe Camera RAW.

Lightroom Tone Curve

Lightroom Tone Curve

What we want to do is to darken the shadows and midtones and slightly lighten the bright areas without losing information – that is to adjust the exposure and contrast. The process is called “stretching the histogram”.  It’s pretty straight forward. Click points on the curve and drag up or down and left or right to create a new curve while paying attention to both the image and the resulting histogram.

Before and After Tone Curve Adjustment

Before and After Tone Curve Adjustment

Can you make these adjustments using Adobe Camera RAW? Yes! The controls are nearly identical.

This is now a good starting point to apply some additional pop, But what if you wanted to do this in Photoshop?

Photoshop Exposure and Contrast using Curves Adjustment Layer

Histogram Stretch using Photoshop

Histogram Stretch using Photoshop

The image above has brought out a bit of pink in the sky, but the dune is a little flat and a little dark. The good news is there is a way to give specific colors special attention – using what we call the “twiddle finger”. You click the hand icon, then pick an area of the image you would like to brighten or darken. The luminosity selected is shown on the graph, then you drag the mouse up or down.

Twiddle Hand curve adjustment

Before Twiddle Hand curve adjustment

 

After twiddling.

After twiddling upward a bit

The twiddling can be repeated. Beware, though, twiddling is global, not local. In general the tone curve should always be flat or upward as you move left to right otherwise you will be lightening dark areas to the point where they become lighter than adjacent light areas.  One way to improve your curve is to smooth the graph. Click the pencil icon then the icon below it (graph adjust), then click the graph (above the pencil).

After a bit more fiddling and twiddling we get what you see below. What more fiddling? Well, we like to add another adjustment curve and select the “Increased Contrast” option.  If things were close to good to start with, the curve might go too far, so adjusting the layer opacity downward is the solution.  In fact, we use the “Adjust contrast curve” so often that we created an action for it and assigned it its own hot key (F9).

640_2

Original Exposure Contrast Enhanced, Histogram Stretched, fully twiddled 🙂

Now we have quite a bit more drama, and much more contrast.  Where are the distractions? What leads your eye away from the interesting parts of the scene?  What are the interesting parts of the scene? Now is a good time to make note of the distractions, because soon we will conquer those.

In truth, we have one more thing to address in the exposure category. The sky is a bit too bright. The solution is to apply a gradient using either Adobe Camera RAW or Lightroom (it can be done in Photoshop but it is harder than it should be, and less convenient).

Graduated Skies – Lightroom

The graduated filter (M) is our friend for not only darkening the sky, but also making other adjustments. That you can make multiple adjustments simultaneously is one thing that sets it apart from the Photoshop methods. Here we have zoomed to 100% to show both a portion of the sky and the location of the graduated filter tool. Note that the sky is a bit “gritty”. We will fix that!

Graduated Filter tool and gritty sky

Graduated Filter tool and gritty sky at 100%

Our sky fix will illustrate one of our other techniques: selective sharpening – only in this case we will de-sharpen to remove the “grit” as follows.

Applying a Gradient to the Sky

Applying a Gradient to the Sky

We use a sky gradient so often that we created a pre-set for it.  The preset reduces exposure by -0.76, contrast by -17, saturation by -24, sharpness by -40, and noise by +100.  Those last two, decreasing sharpness and increasing noise processing result intentionally in blurring. In this case the exposure correction is a bit too strong, but that is easy to fix by bumping the exposure up a little (-0.51).

Let’s look at what this gradient did to our sky. Notice how the grit is just about gone.

gs_2014-02-08_122146

 

If you are thinking that applying a gradient to darken the sky is somehow dishonest, then please don’t use a graduated neutral density filter (GND) which does the same thing at image capture time – but a physical GND does so less elegantly!

Sharpening and Desharpening

We snuck in a trick to desharpen a mottled/gritty sky above, so please read that for one direction. In fact, we find that using noise reduction is often the most effective way to soften because the result – if not pushed to an extreme – is often more satisfying than using any other method. But some things need a little sharpening, like the eyes and hair of people, the boundaries between objects in a landscape.  When we want to do sharpening we never (ok, almost never) do global sharpening.  One reason we do not globally sharpen is it tends to make mottle things more mottled – like the gritty sky we showed earlier.  It seldom makes sense to sharpen clouds or things that are not sharp by their nature.

Indeed in our beach scene there is really nothing that demands sharpening, but all the same, we’ll apply a little bit at the sky/ground border – mostly to help the sea oats stand out a little more. It’s tempting to think that the Lightroom adjustment brush “sharpen” tool is the right one to use here, but often sharpen alone is not as effective. When sharpening is overused it creates odd artifacts. Often the more effective way to sharpen is to use a bit of “clarity” as well as sharpening. Clarity is a local contrast adjustment which has no analog in Photoshop. If you want to use clarity in Photoshop you must bounce over into Adobe Camera RAW. In Photoshop CC you can get a layer into ACR using the Filter -> Camera Raw Filter dialog. Lightroom and ACR are very similar, so lets show ACR here.

Adjustment Brush in Adobe Camera RAW

Adjustment Brush in Adobe Camera RAW

After setting all the adjustments to zero (easy in Lightroom, just double click on each item), we set the Clarity up (+15), and the Sharpness up (+6). Adjust the size, feathering, density and flow of the brush and paint along the horizon and through the grasses.  It’s always better to go a little at a time than to try to go all at once.  When done hit apply or Open.

In Photoshop we often take a completely different approach. Instead we duplicate the layer, label it “Sharpened” then sharpen (using the smart sharpen filter) or noise reduce the entire layer and then mask it all off. We then “paint back in” the areas we want a correction applied to using a white brush on the mask.

Wow. We’ve spent quite a lot of time talking about exposure enhancements and sharpening and desharpening, so spot removal (cloning, healing and cropping) will appear in part 3.

The 5 Most Used Photo Enhancement Techniques

We have been watching ourselves over our shoulders – yeah, kinda weird, right? Our goal is to figure out what it is we do the most to fix and beautify our photography – night photography in particular.  We cover nearly all of these topics in greater detail in each of our NP150 – Photo Manipulation Webinars but we will hit the highlights here. So what are the 5 most used “tricks”?

  1. White Balance / Color correction
  2. Noise Reduction
  3. Exposure and Contrast enhancement
  4. Sharpening (and de-sharpening)
  5. Healing and Cloning

The first two topics are tackled below. The next two in the following article.  Healing and cloning will get it’s own short article.

First to be clear our goal is usually to make a compelling photo, not merely to represent reality. We do prefer realistic over bizarre, but we are not opposed to removing telephone wires and other distractions.  We DO prefer natural looking scenes and eschew the over-the-top contrast and color saturation that seems to be the rage these days.

White Balance

We hate to be the first to break the news, but your camera is pretty clueless about what color white is. The camera will take its best guess. Our experience with night photography is that the camera choice is usually wrong – or at least unappealing. At its core white balance requires adjusting the red, green, and blue colors so that an area that should have a neutral gray or white color is actually gray – not tinged red, blue or green. When shooting at night, understand that every light in the scene – including stars – has a different color bias (tint). Sodium vapor lights for example are horrendous. Sodium vapor lights used in many streetlights are predominately yellow-brown and almost monochromatic. Under sodium vapor lights it will be impossible to achieve a natural color spectrum. You may want to adjust different parts of a night image separately.  You may have to compromise and have a scene that has a bias of a pleasing kind rather than the ugly variety.

Correcting White Balance

The easiest way to make the adjustment in Lightroom or Adobe Camera Raw is with the White Balance tool.  It looks like an eye dropper. You click the tool, then click a gray area of the photo – if there is something that should be gray in the photo, that is. Even a white area is fine (but not an overexposed white). Stars are generally not good choices for gray-scale selection both because they are often over exposed and because many of them are NOT white! In the example below you see a photo of the Ocracoke Lighthouse which is definitely white, not the orange that resulted from sodium vapor lights.

LR_WhiteBalanceExample

The White Balance tool in Adobe Lightroom

ACR_WBtool

Adobe Camera Raw White Balance Tool

The dubious result of getting the lighthouse to its proper color via the white balance tool appears below. The sky and stars are unnaturally and artificially blue.  There are several solutions to this problem: color correct the lighthouse separately or compromise by warming (increasing the temperature) of the selected balance. Or try again by clicking elsewhere!

LR_WhiteBalanceExample_After

By selecting a different location for the gray sample tool a better compromise can be achieved as shown in the photo below. An examination of the scene reveals that the lighthouse is directly lit while the shed (near the bottom of the shot) is not. The shed and other areas in shadow are lit by ambient light reflected from many sources – including sky glow. After selecting the shadow area the remaining white imbalance of the lighthouse can be handled by desaturating using the local adjustment brush – or leave it like it is.

LR_WB_ChoiceB

 

White Balance Correction in Photoshop

The same eyedropper style adjustment can be found in Photoshop, but you’ll have to hunt for it because the “Color Balance” Adjustment is not where you’ll find it!

PhotoshopWB_a

White Balance (gray point) selector of Curves in Photoshop

White Balance (gray point) selector of Curves in Photoshop. The gray point selector is also in the Levels adjustment.

Note that in Photoshop you have two ways to go: use an adjustment layer, or use an Image -> Adjustments -> Curves (or Levels). We recommend using an Adjustment Layer because you can paint on the mask to control the effect and that makes it easy to adjust different parts of the image separately.  To adjust areas separately in Lightroom, use the Local Correction brush and adjust the white balance slider.

Selective Color Balance Correction

Consider the following photo. With the new flight rules, you can use your camera while the plane is taking off or landing.  Here the plane is landing at San Jose International Airport. There are two things about it that are good candidates for fixing. The first is the distracting glare of reflection from light inside the airplane (that’s due to Virgin America’s “Purple Ambiance”).  We’d like to get rid of the distraction and it’s clear we will not be able to simply crop it out without giving up some of the interesting details.

Landing

Glare from internal reflections leaves a blue cast. There is also noise in this one second, ISO 1600 exposure.

The second thing that is noticeable in the 100% (Zoomed view) is the colorful noise in the dark (and light) areas of the photo.  No sky has grit in it – at least not like that!

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100% View of the noise near the wing.

We can tackle both problems separately or at once.  Selectively desaturating, and slightly darkening the blue glare is simple in Lightroom.  Select the adjustment brush (it looks like a face powder brush right below the “Histogram”), dial down the saturation, and slightly dial back the exposure. Then paint on the image where we want the change to occur.  It may be useful to adjust the brush size, density and feathering. Here some feathering is important. We will not try to also increase the noise processing here, because the whole image needs some despeckling.

Below the mask shows where we painted – and not particularly carefully, either!  The Saturation was turned down to -69, and the exposure by almost a full stop. In a brighter sky we might not have been able to darken the touched up area as aggressively.

Attacking the Glare with Local Adjustments in Lightroom

Attacking the Glare with Local Adjustments in Lightroom

The next thing we want to address is the noise. It’s everywhere in this photo. As we will learn in the next article, we often use noise reduction for smoothing things like blue (or dark) skies and in shadows where you would not expect to find details.  Using Adobe Camera Raw for saturation, exposure and noise reduction works the same way as in Lightroom it’s just that the adjustment brush is shaped differently and found in a different place.

The adjustment brush in Adobe Camera Raw

The adjustment brush in Adobe Camera Raw

Out Darn Noise

In Lightroom (and Adobe Camera Raw), there are two simple – and effective ways – to reduce noise in photos. One is to selectively reduce noise using the “Noise” slider of the adjustment brush as we saw with our selective saturation adjustment. Moving the Noise slider to the right increases the amount of noise reduction but does not give you control over what KIND of noise reduction is performed. ACR and Lightroom have specific controls to reduce Luminance noise (dark and light speckles) and Color or Chroma noise (colored speckles). The noise reduction slider with the Local Correction brush does not let you control which type of noise reduction is applied. Sometimes correcting only the luminance noise is the best approach.  Both methods of correcting noise result in some blurring of the photo. How much blurring depends on how severely the sliders are adjusted. There is no formula for getting noise reduction to work well except to be careful not to over do it!  Surprisingly, a little bit of noise makes a better photo. Indeed, there is an option to ADD noise in the “Effects” panel (called Grain). One thing to beware of: using the color noise reduction aggressively will result in loss of star colors in your night sky. In the examples below we’ve brightened the image to make the changes easier to see.

Before any Adjustment

Before any Adjustment, Turning off the default sharpness enhancement.

The noise reduction portion of Lightroom is found in the Details section. Any controls used in this section will apply to the entire image – which is one reason adjustments should be made carefully and deliberately.  The first step we usually take is to eliminate the default sharpening that Lightroom wants to apply.  We would rather selectively sharpen what needs sharpening than doing indiscriminate global sharpening. Next zoom in to 1:1 view of an area (Z key) where noise reduction is needed. For this pick a dark area where some details should be observable. It is also helpful to pick a dark area adjacent to a lighter area where sharpness is desired so the effect of noise reduction can be seen on two elements at once.

We slowly bump up the luminance until we see less “grit”.  Be sure to wait long enough to see the changes made in the image.  We do not generally notice much difference with the detail and contrast sliders, but if we find ourselves adjusting as far as halfway on luminance and not getting what we want, we play with those sub-sliders.

If we still have not achieved the correction we want, we bump the color slider as well… only much more carefully. If there is a LOT of color noise the color noise correction may be the slider to bump first.  Once things are “almost” where we think they look right we choose another area to take a look. It  is important to select an area of the photo that did not need much adjustment – usually a bright area. If the brighter area has become too blurred, we back off on the overall adjustment and then use a local adjustment to add still more noise reduction selectively.

All adjustments made - note that perfect smoothness is not a goal.

All adjustments made – note that perfect smoothness is not the goal!

In Photoshop there are many more ways to reduce noise than those provided in Lightroom and Adobe Camera Raw. Our experience is that the noise controls in ACR and Lightroom are very good – better than any specific filters you will find in Photoshop.  We do use Topaz Lab’s DeNoise photoshop plugin quite a lot however.  The best noise reduction method – when possible is to use the Simple Astrophotography Processing Technique. A photo like the one shown here is not a candidate, however, because that Astro technique requires multiple frames of the same image – that wasn’t possible here with the aircraft coming in for its bumpy landing.

Finished Image

Finished Image

In the next article we will take on the remaining subjects, but you may have already figured out one of the techniques we use for desharpening – aggressive noise reduction!