We see and photograph reflections of light from the surfaces surround us. If objects did not reflect light we would not see them. Upon reflection, however, the quality of the light may change with undesirable side effects for photography. Before it reflects from a surface, light wave moves in all directions very much like a pipe cleaner with its bristles coming out in all directions. When it reflects from a surface, depending on the angle, reflective surface qualities, our angle of observation, the part of all of the light may become polarized. A polarized light wave no longer moves in all directions but in one direction much like a recording tape, flat.

What is a polarizing filter

When polarized light hits the camera lens, and consequently the film or the digital sensor, it records only as a shiny reflection and we do not see the surface from which it reflects. In order to see the surface, we need to remove the polarized light so the non-polarized light could record an image of the actual surface, say water or display window. A polarizing filter performs this task depending on many factors. By rotating it, we bring its “light grill” so to speak perpendicular to the polarized light direction and it cannot pass through the filter, the lens and record the reflection on the photograph. To visualize the concept, hold your hand out with fingers close to each other but not touching, call this the polarizer. Then, take a crisp dollar bill, call it the polarized light, and slide it through your fingers. Now, hold the angle of the dollar bill and rotate your hand, presto, you have created a “dollar polarizer.”

How does it work

Now, this is how it works. But it does not work all the time and at all angles. First, it only works for light that reflects off nonmetallic surfaces. It is not going to do much to remove the reflections from the stainless-steel kitchen sink. Second, it depends on the angle of the light hitting the surface. Light gets polarized when it hits a surface at a particular angle. (I am not a physicist, so I am probably sticking my neck out here, but I think that angle is 26 degrees.) The effect of a polarizing filter depends on the angle of rotation with respect to the camera lens, thus, the incoming light. If the angle is perfect, it may totally remove the reflection and you could see the fish swimming under water. Otherwise, the effect will be partial or even nonexistent.

How to use it

A polarizing filter is very useful in many photographic situations but it really comes to its own in outdoor, nature, and landscape photography where lighting cannot be controlled. Under outdoor lighting practically everything reflects the blue sky and thus lose part of their color depth. A polarizer may remove the reflections on the leaves and make the foliage really show its true color. Reflections on water could be very dramatic if planned or they could be very distracting if polarized light interferes with the photograph. Again, a polarizing filter could remove some or all of the unwanted reflections.

Perhaps, the most common use of a polarizing lens is to deepen the color of bright blue sky, like those you would see on a crisp day. Here, there is literally a “rule of thumb” to use to figure out where the maximum polarizing will occur in the blue sky. As you stand outdoors, under the big blue sky, hold your hand out with only the index finger and the thumb extended. Now, make the index finger and the thumb form a right angle as if you are imitating holding a gun and point your thumb at the sun. Now, when your rotate your hand around the axis of your thumb, your index finger will draw an arc in the sky where maximum polarizing effect will show. The effect will be quite dramatic if the sky happened to have a few decorative white clouds against the blue sky.

May your light always come from the optimum angle.

I would like to hear from you, feel free to leave a comment or send an e-mail a message to me.

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I tried using window cleaners, eyeglass sprays, moist towels with their unique shortcomings. All the liquids I mentioned run to the bottom of the monitor and the moist towels don’t have enough oomph. Then I stumbled on to the idea of putting a dab of Purell, or its equivalent on paper towel and wiping the glass with that. I tell you, it works like a charm, it stays where you put it with no runs racing to get between the monitor and the bezel. These hand sanitizers are thickened alcohol and do a great job on my monitor. I use it to clean the plastic exterior too.
BEFORE you use it on your monitor, try it on the outside edge to make sure that it will not cause any discoloration. Also, do not try this on LCD monitors, they may have a micro etched surface which may not like this treatment.

I am telling you what I do, what you do is up to you.

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Figure 1

Curves First Attempt

As a standard processing step I applied a curves layer with proper white and black points selected which resulted in the full-range but uninspiring image (Figure 2).

The large original looked but only marginally better. I kept fiddling with the contrast, colors, etc. and nothing worked to my satisfaction. I left this image the way it was and started working on a copy of the original again.

Curves multiplied

This time I followed a different approach. I added a curves layer and clicked on OK without making any changes. Then I changed the blending mode to “Multiply” which gave a much darker image but with more character as you see below in Figure 3.

This image obviously has too dark shadows. Now, I went and adjusted the curves layer. I picked the white from the door frame on the left and black from the dark area between the two men. Then opened up the shadows by raising the black point higher as shown in the following screen capture (Figure 4).

The colors looked rich and the picture conveyed the mood of the late afternoon just before the sunset. However, it still had too much contrast. See for yourself, Figure 5.

Figure 5

Although this was a definite improvement over the first curve adjustment (Figure 2) there was practically no detail in the shadows.

Let’s see the difference

I flattened this image and copied it over the original (second picture from the top.) Since I was interested in the difference between the two images, I changed the blending mode to “Difference.” I wanted to capture this difference and apply it on the original. So, I duplicated the background (image 2) and merged down the top dark layer on the background copy. Now I had the original image as the background and the difference as a layer above it. This is how the difference layer looked (Figure 6):

Figure 6

Let There Be “Soft Light”

I changed the blending mode of the new layer to “Soft light” and ended up almost where I wanted. (Figure 6)

Figure 7

Although this image looks like the one in Fugure 5, you can see significant differences between the two in their larger versions. I was not happy with the two man that showed almost no detail.

Get the Blender out

By double-clicking on the top layer I arrived at the Blending options screen and adjusted it as shown below (Figure 8):

Figure 8

The dark control point values are 20/73 in case you cannot read them from the image. As I pulled the dark triangle on the “Underlying Layer” slider, I watched the detail on the men’s clothing magically emerge and blend with the rest of the image. The resulting image is below (Figure 9) and the following that showing the original for comparison (Figure 10):

Figure 9

The original for comparison:

Figure 10

This image conveys what I saw that late afternoon better than any of the above. It has that slight glow before the sunset, colors are dark and saturated with details in the shadows and the highlights. I now have another tool in my tool-chest. You should try the process on a suitable image and see for yourself. It is much easier and much faster to do then to read this tips column. Keep clicking.

I would like to hear from you, feel free to leave a comment or send an e-mail a message to me.

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I face situations where I may want to accommodate a wide tonal range in an image that has too much contrast. I picked a sample image to use here showing two garages with white paint under direct sunlight with a heavy shadow area behind a fence. (Figure 1)

In this tutorial, I will use the combined RGB channel and not be concerned with color corrections. The purpose is to illustrate a technique on controlling the range. You may save and use the image above to follow the rest of the tutorial.

Simple curves adjustment

I made a decent effort to adjust the curves to open the highlights while retaining some detail on the white parts of the garage. Here is the result (Figure 2):

I have managed to adjust the whites and, to some extent, the mid-tones but the shadow area on this side of the fence is still too dark. Here, the split adjustments of the highlights and the shadows will give me a greater control on maintaining the tonal range that I would like.

The mask

First, I need to create a mask that consists of the luminosity of the image. To achieve that, click on the “Channels” tab, then Ctrl-click on the RGB combined channel. This will select the luminosity of the image. Press Ctrl-C to copy this selection. We now need a new channel, click on the fly-out menu arrow on the top right corner of the channels panel and select “New channel” from the menu, accept the suggested name “Alpha 1.” You will see a blank channel. Make sure to click on this channel and press Ctrl-V to paste the image in the clipboard. Now we have a B&W image of the luminosity of the original. Press Ctrl-D to release the selection so that no part of the image is selected. Since I want the mast to control the shadows, I will invert the image before making the final adjustment to create the mask. To do this, press Ctrl-I (making sure that you have already pressed Ctrl-D.)

To make the mask work the way we want, we should enhance its contrast. Summon the “Curves” tool, press Ctrl-M and make the curve to look as follows. The important thing to remember is to create a smooth curve. Here’s my curve (Figure 3).

After this adjustment, my Alpha 1 channel looks like this (Figure 4):

Now I have a high contrast channel that I can use, I want to use it to select the appropriate parts of the original image. Press Ctrl-click on the Alpha 1 channel to select the mask, then click on the RGB channel. The mask has created the selection on the RGB channel which will control the areas that will be affected by subsequent adjustments.

Curves, part I

Now, click on the “Layers” palette and using the black-and-white circle at the bottom of the palette window, create a “Curves” layer. This adjustment layer will only affect the shadow areas of the image and to a lesser extent some of the mid-tones. I have adjusted my curves as follows. This retains the highlights the way they were, makes slight adjustments to the mid-tones, and significant adjustments to the shadows.

The resulting image after this stage looks like this:

I can see more in the shadows, even the reddish patio tiles and other detail are visible.

Curves, part II

Now I will turn my attention to the highlights which requires the exact opposite of the mask that I have created for the shadows. Using the mouse, Ctrl-click on the curves mask, which shows the high contrast B&W image on its thumbnail. (Alternately, you can switch to the channels palette, and Ctrl-Click on the Alpha 1 channel.) We want to mask the exact opposite of the selection, so press Ctrl-Shift-I to select the inverse. Again, using the B&W circle at the bottom of the Layers palette, create a new curves layer which will affect only the selected areas, highlights. Any adjustments we make on this curve will affect the highlights and to a lesser extent the mid-tones. Here is my curve for this adjustment (Figure 7).

Finished work

And the resulting adjusted image has the correct highlights and reasonably open shadows. Since we have both curves layers active, the image shows the combined adjustment and yields full tonal range.

If you think the same result can be obtained by using a single curves layer on the original image, you may be (may be) right. Try it and observe how fussy you have to be to make it look half way decent. Where this method of split level curve adjustments are quite tolerant of substantial adjustments on their respective curves.

I would like to hear from you, feel free to leave a comment or send an e-mail a message to me.

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How it works

Digital polarizer works by mimicking the features of a real polarizer. The technique works best with photographs with blue skies or blue ocean and some unwanted reflections on water. I have successfully used it to achieve richer colors even without any part of the sky showing. The reason it works is very simple. Even though the sky may not be visible as part of the image, its reflection on most surfaces is there as a slight cast of cyan. So, by removing it we can clean other colors of this invisible haze.

Step-by-step

I will start with an image with a large area of what was supposed to be blue ocean. Feel free to copy this image and practice in Photoshop. I photographed the swan at a nearby cove and the water was indeed a nice shade of blue.

I roughly adjusted the curves to get the swan image I wanted. I did not do any color correction in red, green, or blue channels. Now comes the fun part. When I look at this photograph, I want to see the water as blue rather than bluish gray. This tells me I need to work with the “neutrals” and the “blues.”. Now is the time to add a “Selective color” adjustment layer. Either use the shortcut from the bottom of the “Layers” panel or follow the menu options “Layer/New adjustment layer/Selective color.” Using the drop-down color channel selector, click on “Neutrals” and move the sliders as shown below. You may write the numbers if you wish.

Figure 2 Neutral Channel

Each slider here represents primaries and their opposites. Cyan-Red, Magenta-Green, Yellow-Blue sliders add to the labeled color in the positive direction and add to the implied color in the negative direction. So, -29 yellow is +29 blue and so on. After checking the numbers click on OK and look at the image if you are following the tutorial in Photoshop. It should look like the following image.

Figure 3 After Adjustments

We added more blue, more cyan and more black to the neutrals. It looks better than the original but we are not done yet. Now, double click on the selective color channel and this time select “Blues” from the drop-down list. Now we will adjust the blues to the values shown below.

Figure 4 Blue Channel

Adjust the values as shown and click on OK. These adjustments will add to the blues more cyan, more blue, and more black. The result will appear as follows.

Now, I have a pretty close shade of blue for the ocean but I have introduced a bluish tint to the white feathers of the swan. This can be fixed by changing the blending properties of the selective color channel. Right click on the selective color channel and select “Blending options” from the pop-up context menu. We do not want the adjustments we have made in the selective color layer apply to whites. So, we move the slider as shown below.

First move the highlight triangle to the left until you read 190. Then, while holding the Alt key (on PC) click on the left half of the triangle and move it to the left until it reads around 167. This is not an exact number. It simply provides a smooth transition of the effect between that range of brightness. The finished image will have clean whites on the swan and deep blue on the ocean part of the image. Here is mine.

Compared to the original, it is a major improvement if I may so myself.

May your oceans be of the shade of blue you want.

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