Wednesday, August 26, 2009

Review of HiViz kits and initial results

I've always been intrigued with capturing images of things that we don't typically see. One way this is manifested is with freeze shots like splashes, water drops and light bulbs burning out. In the past I've done this using continuous drive mode, strobes and semi-random chance. Wanting to have additional control, last year I purchased a sound trigger, light gate and delay timer kits from These types of projects being the somewhat low priority that they are, I finally finished them a couple weeks ago.

Since I have built many electronics kits in the past, I wasn't intimidated by the projects at all, but I wouldn't suggest them if you've never built a kit before. The kit is basically all the components you'll need with some hookup wire and a couple sheets of paper with schematics and directions. For an initial, temporary build, you can buy breadboards from HiViz and they have detailed pictures on their web site of the kits built on the breadboards. This allows someone not familiar with schematic reading to assemble them, but they're not a very permanent solution. In addition to the kits, I purchased a couple perf boards from Radio Shack and some cases and other miscellaneous items from Ra-Elco to finish the kits off.

In the end, this is what the completed kits look like:

(Click images to see larger view.)

I won't bore you with the specific build details, since there's nothing too exciting about the construction of the projects. But I will say, the timer was the most complicated with the highest parts count and the sound trigger was the simplest with the lowest parts count. Here's what the inside of the light gate looks like:

(Click images to see larger view.)

Probably the most interesting thing is I used 1/8" jacks for all three outputs and the delay unit's input. The Cactus wireless system I have to fire my strobes has one of these in the transmitter. This allows me to use standard audio patch cables to connect the output of the triggers either directly to the wireless transmitter or to the input of the delay unit which in turn can be connected to the transmitter. The sensors for the light gate and sound pick-up each have different types of connectors so it's impossible to mix them up or connect them incorrectly.

Another feature that's not standard with the kits is multiple resolutions on the timer. The delay kit comes with several different values of capacitors that control the maximum time for the delay. The idea presented in the kit is you decide which one you want to use and build your kit with only one of the capacitors. I decided to put a three way switch in so I can switch between them easily. With the values I used, I can switch between a maximum time of 10 milliseconds, 100 milliseconds or 1 second (1000 ms). I don't expect to probably ever need a 1 second delay, but it's there if I do find I need it.

In initial testing, they seem to work pretty well. All three worked correctly the first time I turned them on. The only real problem I've had is the sensitivity and timer delay adjustments don't seem to be active until about 1/3 of the way through the sweep of the potentiometer. After that they seem to work as expected. The panel mount ones I used are rated the same as what came with the kit so I'm not sure exactly where the problem lies. I have a couple ideas, but they work well enough I'll probably never dig into the reason; I'm more interested in using them than tracking down this anomaly.

My first test shots were with the sound trigger and delay timer. I setup my lights and camera in my "studio" (aka workshop, basement, storage) and plugged everything together. I set my camera to manual mode and took several test shots to dial in an acceptable exposure and then put it in bulb mode and put my remote release on it. Then I loaded my Airsoft gun, turned off the overhead lights, tripped the shutter and shot some balloons. In total, ten balloons gave up their short lives as I got the trigger sensitivity and delay dialed in. In the end, the last three all gave me very similar results. This proves to me I'll be able to get the consistency in these shots that I've been looking for.

Here are a couple of the better test shots. I'm looking forward to being able to spend some time getting some better shots setup and playing with these a lot more.

(Click images to see larger view.)

Thursday, August 20, 2009

How to make a surreal faux HDR image


I recently ran across this Russell Brown PhotoShop tutorial wherein he presents a technique to make what he calls a Faux HDR image. This doesn't really have much to do with HDR other than taking a single image and giving it a surrealistic, over-the-top, tone-mapped HDR look. It does not take a scene and get more dynamic range out of it as is typical with HDR. It does take a scene with a compressed dynamic range and expands it to make it brighter while at the same time it boosts color brightness and saturation. You can go watch the video here or, if you're like me and aren't a fan of video tutorials, you can read about it below.

Best types of images

This technique works best on images that are not blown out but where the detail is tightly compressed. Typically this happens when a scene is exposed for a bright section, so it's not over exposed, but has lots of dark areas causing important detail to be hidden in the shadows. For the purposes of this tutorial, I'll be using this example image I took on a recent Photowalking Utah event.

As you can see from the histogram, this image has a large bump on the left and a smaller bump on the right indicating a lot of dark and light areas whereas the middle area does not have much going on. The dark areas are not underexposed nor are the light areas overexposed. This can be seen by the two triangles in the top left and right corners. The one on the left will change color when there are details lost in the shadows and the one on the right when the brightest areas are overexposed.

For comparison, here is a similar image that does not work well. It is exposed for the darker areas as evidenced by the wider and smoother bump on the left side. Unfortunately, this causes the highlights to be overexposed and the cloud detail to be lost as seen by the sharp spike on the very left side.

In Camera Raw

The majority of the work will be done in Camera Raw, prior to going into PhotoShop. First, open your image and verify there are no blown out details. As intimated earlier, look on the histogram for images without spikes going off either edge. If you click on the triangles at the top right and left corners of the histogram, Camera Raw will change all the overexposed sections to red and the underexposed sections to blue as a means of highlighting the areas that have lost detail.

Now to get into the main changes. We're going to be manipulating primarily the Exposure, Recovery, Fill Light, Blacks, Clarity and Vibrance sliders. We'll start at the top of the list and work our way down. When we get to the bottom, we'll evaluate the image and possibly go back to the top to make some fine tuning adjustments.


The exposure will typically need to be adjusted. If on the histogram, the dark area is larger, such as on this example image, then typically the exposure will need to be increased. On the other hand, if the bright area is larger, then it'll need to be decreased. On this image, if I increase it at all I'll start blowing out details in the bright areas, so for now I'll leave it at 0.


Recovery pulls the brighter parts of the image down and gives us some headroom on the right side of the histogram to additional changes. This technique typically works best with this set the maximum, so that's where I'll put it for now.

Fill Light

Fill Light brightens the dark areas without blowing out the highlights. Again, the images that work best with this technique usually like this set to the maximum.

Now that we're about half-way through this first part, we can see our image is quite a bit brighter, but has sort of a flat appearance to it.

We can see in the histogram the data is spread apart rather than being bunched up on the two sides. The remaining steps in this section will help give the image some more depth.


Now to get rid of that flat look, we're going to increase the Blacks slider. Adjust it so the dark regions are just starting to clip, as indicated by the blue highlights that Camera Raw shows us. For this image, a value around 40 works well.

Clarity and Vibrance

To get that surrealistic look characteristic of overly tone-mapped HDR images, we're now going to slide both the Clarity and Vibrance sliders all the way to their maximum values.

Fine tune adjustments

Now that we have all the basic adjustments done, we need to evaluate where we are. At this point, this image is still pretty dark. To lighten it, I go back to the Exposure slider and find I can now push it quite a bit. In fact, I can increase the exposure by 2.5 stops without clipping. If I increase it more, then I start blowing out my sky which I don't want to do. By leaving detail in the sky, even though it's not too visible at this point, I'll have something to work with later to improve it.

Now we're done with the controls on the first panel.


The next step is to do some adjustments on individual colors. To do this we go to the HSL / Grayscale tab.

And once there, we click on the Luminance tab.

These controls allow us to change the brightness levels of various color groups. What we change and the amount we change it will vary from image to image. On this image, I find that decreasing the Blues and increasing the Purples significantly helps my sky. Based on this discovery, I go over to the Hue tab and find I can help the sky some more by sliding the Purples and Oranges over to the right to around 65. This brings out the colors in the sky and flowers even more. This is an area where experimentation on each image can yield dramatic results.

If you so desire, you can crop the image and apply a vignette. The cropping tool in the top toolbar works well to remove those parts of the image you don't want and the vignette control on the Lens Correction tab allows you to highlight the center of the image. I choose not to do that on this particular one.

Open in Photoshop

We're now done with our edits in Camera Raw. Just prior to opening the image, make sure the color depth is set correctly and smart objects is enabled. To do this, click on the label that is centered at the bottom of the Camera Raw screen containing information about the color mode, bit depth, image size and resolution. This will open a dialog. Make sure the Depth is set to 16 bits/channel and the checkbox for smart objects at the bottom is checked. Close the dialog and then click the Open Object button. Doing this will ensure there is no loss of color information in the transfer to Photoshop and the background will be configured as a smart object so edits will be non-destructive.

There are many things that can be done to the image at this point. One of the more common ones for this type of image is to adjust the Shadows and Highlights found on the Image / Adjustments menu. Quite often this type of image can be further enhanced by selectively adjusting contrast in different regions of the picture. I found on this particular one this didn't help, but it has on others.

Sharpening is another thing that typically enhances most images. The use of either Smart sharpen... on the Filter / Sharpen menu or my High-pass sharpening action can be used. The Smart sharpen tool can give a very edgy look by pushing the controls to high values. My action will give a less edgy look.

After some tweaks to the sky, this is my final version of this image.

And here are a couple of other images processed with this technique.
Albion morning

Red, White and Blue


In closing, here is an outline of the steps covered above.
  • Camera Raw
    1. Exposure: over or under as dictated by image.
    2. Recovery: typically 100%
    3. Fill Light: typically 100%
    4. Blacks: typically 30-50%
    5. Clarity: typically 100%
    6. Vibrance: typically 100%
    7. HSL / Luminance: as needed for iamge
  • Photoshop
    1. Image / Adjustments / Shadows and Highlights: as needed
    2. Filter / Sharpen / Smart sharpen: as needed
    3. Anything else: as desired

Monday, August 10, 2009

Photoshop CS4 action: High-pass sharpening

My good friend and fellow photographer Rich Legg wrote an article almost two years ago about how to use the high-pass filter to sharpen an image. I made a mental note of it in passing, but didn't do much with it since I was using Paint Shop Pro at the time and it has a built-in method to do this in one step. When I switched to Photoshop several months ago, I went back to his article to remind myself how to do it.

In his article, Rich outlines the four step process:
  1. Copy the layer you want to sharpen.
  2. Apply a high pass filter to it.
  3. Set the radius to around 4.
  4. Set the blending mode to Soft light for a mild sharpen or Overlay for a stronger effect.
Simple as this is, I created an action to make it a single operation. The action file can be downloaded here.

To use it, click the link above and save the file to your computer. In Photoshop, on the Actions menu, select Load actions. In the open file dialog, go to the location the file is saved, select and open the file. You should get a action group called HP3's sharpening with two actions in it, one for strong sharpening and one for mild sharpening.

To use them, open an image, highlight the background layer, click on one of the two actions and run it. You should get a new layer and the high-pass filter radius dialog. Adjust the radius as desired and click OK. You should see your image sharpened. You can enable and disable the layer to see the effect of the action.

A couple notes:
  1. The radius value of 4 that Rich recommends for the filter is image dependent. Use higher values for more sharpening and/or a larger image. Use a smaller value for less sharpening or a smaller image. The actions I've recorded use a value of 5 as a default since I've found that seems to work better for me with the types of images I typically work with. If you set this too large, you'll get a light halo effect around the edges of subjects in your image.
  2. I've set the Opacity of the sharpening layer to 50% as a starting point. Again, this seems to be a good starting point for me on the images I edit. Like the radius value, it can also be increased for more sharpening or decreased for less.
If you have any questions, problems or suggestions, leave a comment and I'll try to address the issue. Have fun!