Sensor Dust

If you own a digital camera, chances are you have sensor dust. It gets in there somehow, and can make your life a living hell. You can spend a lot of time in Lightroom and/or Photoshop removing dust. but chances are you are missing lots of it.

Unless your aperture was set to f16.0 or higher changes are those dust bunnies are just blurry blobs that are hiding in the corners of your image. You need to use the following trick to find those guys and get them out of there.

The easiest way in Photoshop is to:

1. Create a Curves adjustment layer
2. Create a point at about 25% and drag it upwards towards the top.
3. Create a point at about 75% and drag it downwards towards the bottom

Voila! 

Now look again and be amazed. All those dust bunnies, blemishes, loose hairs, scratches, etc. just pop right out at you.

When you are done editing simply drag that adjustment layer to the trash.

Enjoy.

Busy Busy Busy

I recently returned from a trip to Eastern Europe where I spent five weeks travelling. It was a blast!

We visited the following countries in no particular order:

• Germany
• Czech Republic
• Poland
• Slovakia
• Austria
• Hungary

We saw many things, but what shocked us the most was the sheer age of everything. In North America you are lucky to find buildings more than a 120 years old. There we visited churches that were celebrating their 950th birthdays!

We saw numerous castles most in ruins, but a couple which were still in pretty good shape. We also saw many Churches, Cathedrals, Basilicas and Chapels. We even visited a Synagogue and an Ossuary. I am not a religious person, but the sheer beauty of these places was beyond belief.

In Budapest I met up with a colleague from work who was visiting with her daughter. We spent a fantastic evening wandering the city and then having a great dinner at a local restaurant.

We also went to see an exhibit at the National Museum in Budapest celebrating the centennial of the famous photographer Robert Capa. He was an amazing war photographer. He died in 1954 by stepping on a land mine while photographing in Vietnam. I would highly recommend this exhibit if you are in the area.

The biggest hurdle now is that I have to download, process, backup and export all the images I took. With over 5000 images on 8 SD cards it will take quite some time to go through.

Stay tuned for more images and stories.

RAW vs. JPEG

The debate over RAW vs. JPEG has been around since digital photography existed. Unfortunately it is not as black and white as people try to make it out to be. Each format has its uses and like any tool at your disposal, it's all about knowing when to use it.

RAW

This file format is the raw data captured by the cameras sensor. Nothing is done to the data, it is lossless. It is written to the file as it is captured. The camera makes no assumptions about how it should interpret the data. The camera records all the relevant settings on the camera like aperture, shutter speed, ISO, lens data, white balance selection, etc. 

JPEG

Stands for Joint Photographic Experts Group. The format was released in 1992 for use on the web for photographic images. It is a lossy format, in that data is discarded when the image is created. JPEG is a visual format and is designed for perceptual viewing. The algorithms it uses to encode the data rely on the fact that the human eye can't see certain small changes in an images colour, contrast and details.

When recording a JPEG image you can select the quality of the image. This determines how much data is preserved in the final product. Cameras usually describe this as Basic, Normal and Fine. In software such as Adobe Photoshop this is usually a percentage from 1-100. The higher the percentage the less information is discarded. The downside is that the file is larger in size.

Comparison

File Sizes

The chart below shows a simple example of a single image comparing a RAW image to the same image saved as a JPEG. The JPEG image can save a lot of space on your cameras memory card or computer hard drive. At 90% a JPEG takes about 1/3 the space of a RAW image.

Below 50% JPEG images start to show compression artifacts. The image may start to look blocky. This is due to the compression algorithm used. It really depends on the image, but generally darker areas show this effect sooner than highlights. Since cameras usually only have 2 or 3 JPEG settings selecting Normal is probably the lowest you should go.

Percent %	10	20	30	40	50	60	70	80	90	100
RAW Size (Kb)	n/a									33075
JPEG Size (Kb)	653	785	919	1152	1626	2643	3919	6067	10046	14868

Bit Depth

Raw images can be anywhere from 10 bits / colour channel all the way up to 14 bits. JPEG images are limited to 8 bits. For the average person this is gobbledygook. Where it matters is when you need to edit the image. The higher the bit depth of your image the more data that is recorded. This is the crux of the argument of RAW vs. JPEG.

A 14 bit RAW image captures 2¹⁴ bits / colour channel which is 16384 distinct shades. On the other hand a JPEG image has 2⁸ bits / colour channel or 256 distinct shades. Please refer to the image below to see a comparison of the various bit depths.

Strengths

JPEGs

• great for viewing
• widely supported format
• very small file sizes
• saves quickly (great for sports or journalism)

RAW

• more data for editing

Conclusion

So like most things in life it really depends on what you want to do with the end result. If you intend to edit the image you should be shooting RAW. RAW images are also better since it a record of the sensor data as captured by the camera. It provides proof that the image has not been tampered with and requires specialized software to view it.

If you are just taking snapshots and are simply going to upload them to Facebook or Instagram then JPEG is probably the better choice. Also if you take lots of photos then JPEG might save you some money since RAW images are so much larger in size.

PS: When I go out shooting I shoot both RAW and JPEG. Why? My camera supports two memory cards. So the first card has all RAW images and the second card has all JPEGs. This is for safety just in case one card dies. The second card also allows me to upload JPEG images right away if I need to.

More Information

To learn more about RAW images check out https://en.wikipedia.org/wiki/Raw_image_format.

To learn more about JPEG images go to https://en.wikipedia.org/wiki/JPEG.

Processing a Landscape Image

Exposure

The first exposure I took of this scene (N) looked flat and lacked highlight and shadow detail. It was taken at 1/13th, f5.6 at 100 ISO. I then bracketed the scene -2 and +2 stops to ensure that I would capture the highlight and shadow detail. 

If your scene has more exposure latitude than this, you will need to bracket further. I am not sure why Nikon decided that the maximum bracket is 1 stop on their cameras. They need to fix this!

NOTE: when you are bracketing exposures it is very important that you do not adjust your cameras aperture or move the camera. If you do, the images will not merge properly since the depth of field/focus will vary. You must vary your shutter speed, so it is recommended that you use your cameras Aperture Priority (A or Av) mode. Using a sturdy tripod will ensure that the camera does not move and I also recommend manually focusing your scene.

 Below are the resulting 3 exposures.

HDR

There are many tools available for merging exposures into a single image. Photoshop, Photomatix, HDR Efex Pro, etc. They all perform the same function of blending multiple images into one. This single image is called a High Dynamic Range (HDR) image. A normal photograph is 8 to 14 bits, where as a HDR image is 32 bits.

bits	detail per color channel
8	256
12	4096
14	16384
16	65536
32	4294967296

As you can see from the table above a 32 bit image can retain a lot of detail! JPEG images are 8 bits and are optimized for viewing on a computer screen. JPEG images are highly compressed and therefore information is lost and cannot be recovered. This is why it is preferred to shoot in RAW, as that mode captures more detail and the image is not compressed. RAW mode is usually 10-14 bits in most cameras.

Once you produce your HDR image in the tool of your choice you will need to compress the exposure in the scene to something more suitable for editing. This is usually a 16 bit image. In Photomatix one of the common processes for doing this is called tonemapping. Other tools offer other options and effects.

HDR has a love/hate relationship with people. This is because it can get overused and can create some truly scary/awful results. Like most things in photography it is knowing when to use it and how much that make the difference. HDR is a tool and should be used only when required.

Below is the HDR image which has been tonemapped and reduced to 16 bits.

HDR image (tonemapped)

Photoshop

Inside Photoshop you can alter the image as much or as little as you want. I create a new layer for each new effect, and I use adjustment layers whenever I can.

Dodge/Burn Layer

Creating a dodge and burn layer in Photoshop is quite easy and recommended. You can do everything to the image itself, but this way you can undo mistakes with ease. 

1. Create a new layer
2. Fill with 50% gray
3. Set layer blending mode to Overlay
4. Choose the new layer
5. Select either the dodge or burn tool
6. Ensure that the exposure is < 20% and the brush has a soft edge.

Below is the result of dodging and burning the image. I turned off all the other layers so only the dodge/burn layer were visible. Areas that were burned are darker (more exposure) and areas that were dodged are lighter (less exposure). These tools are named after their darkroom equivalents.

Dodge/Burn layer

Original image plus the dodge/burn layer with blending mode set to Overlay.

HDR image plus Dodge/Burn layer

I then created a Levels adjustment layer and created a mask to only affect the sky. I adjusted the levels to bring out detail in the clouds and horizon. I created another adjustment layer and adjusted the color saturation and vibrance of the image. Below is the resulting, finished image.

Final touches (Curves, contrast, saturation)

Making of an Image

In this tutorial you will see how I edit an image and learn how to apply a dodge/burn adjustment layer in Photoshop.

Step 1

This is a SOOC (Straight Out Of Camer) image. I took this with a Nikon D800 and 105mm Macro lens at 1/250th, f5.6 100ISO.

SOOC (straight out of camera) image

Step 2

I imported the image into Photoshop and did some basic editing. First I removed the distracting branch and flowers in the lower left corner to give the image some negative space. This helps to draw your eye into the image and to the subject. First I selected the entire area using the Lasso tool and then selected Fill and chose content-aware fill. Secondly I used the healing brush to fix any areas that didn't look right.

I also adjusted the color balance to make it warmer. I then zoomed into the image and went around it looking for dust, bugs, and other distracting bits of stuff and removed them with the healing brush. It is usually best to create an empty layer and then apply your healing brush changes to that layer. Just make sure to set it to sample all layers.

Before you start the next step you should duplicate all the layers and merge them into a single layer.

Edit image

Step 3

Now I ran some filters against the image to apply some effects. I performed another Iris blur with a heavier blur on the outside. I then added a curves adjustment layer to increase the contrast of the image. Next came a slight vignette and finally a slight guassian blur. The last effect was a color balance adjustment layer to warm the image.

Filter image

Step 4

The next step is where things get cool. I found that the image has some areas that are too dark or too light. To fix this most people will use the dodge or burn tool. What they don't do is use a layer mask to do it. To perform this you need to create a new layer and fill it with 50% gray. You then set the layer mode to Overlay. Since the adjustment layer is filled with 50% gray and is set to overlay the end result is no change to the image.

You then select the Dodge or Burn tool to lighten or darken areas of the image. Make sure to select a feathered brush and set its exposure to 10-30% and check protect tones. With a low exposure setting you apply the dodge or burn effect in small amounts. A soft brush avoids harsh edges. Protecting the tones avoids color shifts in the effect.

If you turn off the other layers you can see the changes to the dodge/burn layer. Whiter areas are dodged and darker areas are burned. 

Dodge/Burn Layer Mask

Step 5

Turn on all layers and you have the finished image. Enjoy.

Finished image

You can see a larger image on my Google+ page here.