A Guest post by Dave Ware from Whalebone Photography.

This note is aimed to be a quick discussion on High Dynamic Range and possible future enhancements to improve it.

What is High Dynamic Range?

High Dynamic Range is a digital processing effect used within photography to combine a number of images of differing exposures to create a consistently exposed picture throughout the entire frame. This increases the luminance (amount of light) visible within an image.

Why is it required?

The camera’s limitation of amount of colour and luminance it can record is governed by the sensor’s capability and the dynamic range of the camera’s electronics. For example, the Canon EOS 40D uses a 14 bit analogue to digital converter which digitises the analogue signals received from the sensor. The 14 digital bits allow 16,384 different colours to be recorded within the camera.

Looking a a histogram, the horizontal axis is the level of luminance of an image. The vertical axis represents the amount of the image which contains that level of light. For example, a histogram with a single line at the left hand edge shows that the image is purely black. Likewise, a single line at the right hand edge represents an image which is purely white. The amount of data which may be compressed within the histogram is limited by the dynamic range of the camera. A very low dynamic range results in the horizontal axis limits close together. A high dynamic range places these axis far apart.

Here, the exposure of the camera has been set for the balloons – this was chosen as the balloons were the subject of the image and the trees in this case were used to ‘frame’ the balloons. The histogram shows the spike on the left of the histogram representing the trees, and the data on the right represents the balloons and sky. If the photographer wanted both the balloons and the trees exposed then a compromise would have been required so that the balloons become slightly over-exposed and the trees only slightly underexposed.

The above image shows the traditional compromise – the sky has lost some of its saturation in colour, but the trees have retained some detail. Notice also that the histogram shows a slightly narrower spike on the right hand edge (the balloons are now slightly over-exposed), and the left hand edge indicates that more detail is present (the trees are no longer a complete silhouette).

So, to overcome this, the photographer may take a photo exposed for the background and then another photo exposed for the foreground. A few other photos are usually taken between these 2 exposures.

When combining each image, a visually pleasing picture is created and the effects can be quite dramatic. This is the basis of digital HDR. A quick Google search will provide some more examples.

The Future of HDR

Currently, HDR is a post-processing technique, but as cameras advance, its possible that this is an area which may be really improved by manufacturers.

The dynamic range of the camera is likely to be improved. The 14 bit ADC mentioned above allows 16,386 colours to be recorded. 24 bit ADCs have been in manufacture for many years which would allow a total of just under 17 million colours to be recorded! The sensor would have to be capable of matching this dynamic range and the camera’s internal processor would have to be capable of processing the data. This capability exists already as is evident in home computers which have operated from 32 bits for years and are now up to 64 bit processing. Whether or not the sensor is capable of this is another matter for discussion and the additional processing required would increase the amount of time to write the data to the memory card. This may limit the number of full speed frames taken before the cache is full and the camera writes the images to the memory card. These drawbacks are perhaps what is impeding the development of increased in-camera dynamic range as with many advantages, there is often a draw-back.

Another ‘in camera’ technique may be to use numerous sensors within the camera. If one sensor and accompanying electronics can be capable of a certain dynamic range, then 2 sensors may be used to increase the overall dynamic range. For example, one sensor can expose for the highlights and 1 sensor can be used to expose for the shadows, thus creating a higher dynamic range. Sensors can be made incredibly small – just look at the size of phones which have numerous megapixel cameras, and so it’ll probably be no issue squeezing 2 sensors (or more!) into a single camera. However, as the sensor size decreases, the noise of the recorded image (the ‘grainyness’ of the image) becomes greater. Once again, this is a trade-off between high dynamic range, image quality and size.

Another method could be to use an alternative tone-curve algorithm which is currently generally applied to images within the camera. When a photo is taken, signals from the sensor are turned into digital bits and sent to the camera’s computer. To make sense of these signals, the computer processes the data and turns them into something meaningful. This is a form of tone curve. Normally this is employed over the entire image as an ‘average’. Modern techniques however can apply an individual tone curve to every single pixel within the image. This can render a image exposed in a similar manner to that seen by the human eye (ie with a higher dynamic range). This inevitably will increase the processing time within the camera, although as the current method of HDR imaging is to take numerous photos at different exposures, the additional processing time for one single image is probably still a huge time saver.

This new tone-curve method is being advance by companies and Samsung has recently purchased a license to use the technology.

Perhaps other manufacturers have an alternative method, or do not consider high dynamic range of high importance in their cameras, or are just biding their time. This technology is still developing and is an exiting area of camera technology especially as the mega-pixel battle is becoming old news.

The Canon EOS 500D has been replaced with the Canon EOS 550D today, and by the looks of it, replaced with style.

*Images to follow*

• 18MP

• 1080p HD Movies

• ISO 6400

United Kingdom / Republic of Ireland, 8th February 2010 – Canon today announces a groundbreaking new addition to its expanding, world-famous EOS range of Digital SLR cameras – the EOS 550D.

The EOS 550D redefines the boundaries of Canon’s consumer DSLR range, incorporating technologies and features more commonly found in semi-professional DSLRs into the compact, lightweight body favoured by consumers. With a newly-developed 18 Megapixel (MP) APS-C CMOS sensor, coupled with Canon’s advanced DIGIC 4 image processor and the ability to shoot Full HD movies, photography enthusiasts are empowered to explore new levels of creativity.

Creative control with no compromise on quality.

The EOS 550D makes Canon’s powerful imaging technology more accessible to consumers. Canon’s advanced DIGIC 4 image processor and 18MP sensor support standard ISO settings of 100 – 6400 (expandable to 12800), while enhanced in-camera noise reduction technology boosts performance in low light conditions. The system’s 14-bit image processing also produces smoother tonal gradation and natural looking colours for high quality prints and on-screen display.

For swift and accurate focusing, the EOS 550D features a 9-point AF system with one extra-sensitive cross–type point at the centre for f/2.8 or faster lenses. The EOS 550D also supports high-speed, continuous shooting at 3.7 frames per second (fps). These features provide users with the opportunity to exert greater control over their images, allowing them to capture split-second moments with ease and accuracy.

Continuing Canon’s tradition of filtering new technology and features down from its advanced and professional DSLR ranges, the EOS 550D includes the iFCL metering system first launched in the EOS 7D. New for EOS is the ability to set the top limit for automatic ISO, allowing users to control the maximum amount of noise in their images. In a first for entry level EOS, exposure compensation and bracketing can be set up to plus or minus five and two stops respectively, allowing the photographer to take a number of differently exposed versions of the same shot to ensure they capture a well-exposed image, even in difficult lighting conditions.

“Digital SLR photography has captured the imagination of consumers globally,” said Kieran Magee, Director of Product Planning, Consumer Products, Canon Europe. “Every year, more and more individuals are looking to record key life events with unrivalled quality or to test and explore their creativity. The EOS 550D redefines the entry level DSLR category, putting technologies and features previously the preserve of the professional into the hands of the consumer – allowing them to achieve outstanding results. With the EOS 550D, consumers are free to explore the limits of their own creative vision.”

EOS Movies: Full HD video with creative control.

As the ability to record Full HD video becomes increasingly important, Canon continues to deliver DSLR technology that sets the industry benchmark for multimedia functionality. The EOS 550D records video in full 1920×1080p HD resolution, allowing photographers to select the frame rate preferred from 30, 25 and 24fps, as well as offering 720p video at 60 and 50fps. The EOS 550D also includes a 3.5mm stereo microphone socket, enabling the use of an external microphone when capturing video.

Photographers can also take manual control over exposure settings, changing the depth of field and degree of motion blur to shoot more creatively. To provide the best possible video quality, highlight tone priority (HTP) can be set independently for movie capture, without changing any still image capture settings. In situations where the subject is further away, the EOS 550D Movie Crop function records with the central 640×480 pixel area of the sensor, creating an effective magnification of approximately seven times. The EOS 550D is the first in the EOS range to feature Movie Crop and gives consumers more flexibility to capture important moments which would otherwise be too far away.

A clear view of your world.

The EOS 550D also allows photographers to view their images and video in unhindered clarity. A 7.7cm (3.0”) 3:2 Clear View LCD screen with 1,040k dot resolution makes it possible to see 100% of captured images with no borders. The anti-reflective, water-repellent coating also makes it easier to see the screen in bright conditions and from a variety of angles.

EOS build – Canon quality.

As consumers would expect from an EOS DSLR, the EOS 550D is built to a high quality specification. It features bigger, more intuitive buttons which have been redesigned following feedback from users. Based on this feedback, the EOS 550D also features an additional button on the new, battery grip, allowing aperture settings to be changed when shooting with the camera in a vertical position, without having to reorient the body.

Share the moment with friends and family.

For EOS 550D photographers, shooting great pictures and video is just a first step. Thanks to an integrated HDMI port compatible with High-Definition Multimedia Interface – Consumer Electronics Control (HDMI-CEC), video and images stored on the EOS 550D can be viewed on an HD-ready TV and controlled via the TV remote.

For users who want to transfer content wirelessly, the EOS 550D includes Eye-Fi connected functions. The EOS 550D features a dedicated Eye-Fi section in the User Interface and it disables the automatic power-down function when an Eye-Fi card is transmitting – allowing users to transfer content easily and without interruption.*

Accessories

The EOS 550D is fully compatible with all Canon EF and EF-S lenses and EX series Speedlite flash units, including the compact Speedlite 270EX. The EOS 550D is also compatible with the new RC-6 Remote Control, allowing photographers to capture high quality stills and Full HD video without touching the camera body. The slim line infrared controller can trigger the shutter release from up to five metres away, with users able to select either immediate release or a two second delay for greater flexibility when shooting. As well as supporting EOS 550D, the RC-6 is also compatible with the EOS 450D, 500D, 7D and 5D Mark II.

CANON iMAGE GATEWAY – share your stories

Owners of the new Canon EOS 550D can join the CANON iMAGE GATEWAY, a free online facility for Canon users that makes it easy to share their photos and video. Users can take advantage of up to 2GB of personal storage space, creating enough room for hundreds of high-quality images. Mobile browsing is also supported, making it easy for friends and family to view photos on the move.

Features at a glance:

18 Megapixel APS-C CMOS sensor

DIGIC 4 processor with ISO 100-6400 (Expansion to 12800)

Continuous shooting at 3.7fps

Full HD movie recording with manual control and selectable frame rates

7.7cm (3.0”) 3:2 Clear View LCD with 1,040k dots

iFCL metering System with 63-zone Dual-layer Metering Sensor

Quick Control screen to change shooting settings

Exposure compensation +/-5 stops.

Select maximum value for Auto ISO

External Microphone socket

Movie crop function

Eye-Fi connected functions compatibility

A Guest Post by Robin Ryan

I’d like to talk today about the potential offered by Neutral Density filters, and how they can make your photos more unique.

Ruined Harbour II by Duncan_Smith (used with permission)

The smooth watercolour feel in the above photo is due to a Neutral Density 64 Filter. This filter has interested me lately and this photo demonstrates one of its primary uses: to smooth out water and skies without the use of post-processing. I think the results are perfect, and I’d love to have this on my wall.

A Neutral Density Filter is one designed to block out a substantial amount of light. This enables the photographer to slow down his shutter speed and/or shoot at a faster F-stop.

Most photographers will use what is called an N2, N4, or N8 filter to smooth out waterfalls, rivers, oceans. This photographer has used an N64 filter which is far stronger, letting him have an exposure of 60 seconds at f/16 for this image. Without the filter, the photographer would have had to use f/2 to get away with a 60-second image, or less than a second at f/16.

An N64 filter allows for 1.5% of available light to enter the lens. Here is comparison table for the other filters, courtesy of wikipedia:

Filter Name F-Stop Reduction % of Light Transmitted

ND2 has an F-Stop Reduction of 1 which means 50% of the light gets through
ND4 has an F-Stop Reduction of 2 which means 25% of the light gets through
ND8 has an F-Stop Reduction of 3 which means 12.5% of the light gets through
ND64 has an F-Stop Reduction of 6 which means 1.56% of the light gets through
ND1000 has an F-Stop Reduction of 10 which means .1% of the light gets through

Options

It’s important to remember that filters are designed to fit your lens circumference. Look at the front part of your lens and check for a 2-digit number followed by mm. Common circumferences are 77mm, 72mm, and 52mm.

Diptychs and triptychs are a brilliant tool for photographic storytelling. They present two or three images which can be from the same session or they can be polar opposites to show opposition or contrasting ideas. Below are 5 such images and what we can get out of them to help us form our own effective diptychs and triptychs.

1. {Zoom} This beautiful diptych uses zoom to focus on the two main elements of the image and cuts out the space in between.

2. {Tell a story} Or a joke for that matter! This clever diptych from Kimberly Chorney was created to illustrate her son’s joke: What do snowmen eat for breakfast? Frosted flakes!

3. {Lapse} Illustrate a lapse in time or activity. Morning vs. night, old vs. new, dirty vs. clean.

4. {Succession} This triptych is three frames in succession to show you more than just one nanosecond in time. I find this style very effective for shots of children who move so quickly and change their expressions continuously.

5. {Oops} experiment with the mistakes. When first going through the images caught in this session with my kids, I could have easily discarded the out of focus shot on the left. But paired with the in-focus on the right, it just seems ‘right’ somehow. Experiment and withhold the urge to hit ‘delete’. You might find the mistakes are actually keepers when paired in a diptych.

We would love to see your examples. Did you know you can add images to the comments below? Give it a try!

I think most people have seen motivational posters in their travels. You know the ones – they have an image in the middle – a large word underneath and often a saying or quote that is supposed to inspire and motivate you for your day ahead.

This weekend your challenge is to create a motivational poster of your own and to share it.

Image by kkimpel

You might choose to make a serious motivational poster or do a funny one (my personal favorite)- the choice is completely up to you.

Once you’ve taken your shot and created your poster come back to this post

Once you’ve taken your photo and created your poster, upload it to your favourite photo sharing site and either share a link to it below or embed it in the comments using the our new tool to do so.

If you tag your photo on Flickr, Twitter or other sites with Tagging tag it as #DPSMotivate to help others find it. Linking back to this page might also help others know what you’re doing so that they can share in the fun.

Image by Oplotnik

Image by ellie_4_jc

Image by lintmachine

DepositFiles
hotfile.com

The field of perception is devoted to explaining the operation of the senses and the experiences and behaviors resulting from stimulation of the senses. Perceptual processes such as recognizing faces, seeing color, hearing music, and feeling pain represent the actions of complex mechanisms, yet we usually do them easily. The Encyclopedia of Perception presents a comprehensive overview of the field of perception through authoritative essays written by leading researchers and theoreticians in psychology, the cognitive sciences, neuroscience, and medical disciplines. It presents two parallel and interacting approaches: the psychophysical, or determining the relationship between stimuli in the environment and perception, and the physiological, or locating the biological systems responsible for perception. Are there any processes not associated with perception? Surely there are, but the pervasiveness of perception is truly impressive, and the phenomena of perception and its mechanisms are what this encyclopedia is about.

The size of a digital camera sensor has a big impact on image quality, especially when taking photos in low light.