Digital Imaging Q&A text & photos

On the right are the original versions of images used in the feature.

QUESTION ONE
I have an enormous number of slides and negatives and would like to scan them. The problem is many of them are in a bad state, covered in dust and scratches. I've tried using the Photoshop cloning tool, but with hundreds of tiny specks of dust it takes an eternity. Is there any software package available which can help me?
Ian Dogherty

AIDAN'S ANSWER

I know the feeling. I've been digging through my old slides but many of them are covered in dust, scratches and scary looking fungal growths shaped like spiders. It's a shame because the pictures are ideal candidates for colour and tonal enhancement, but unless you can get rid of those marks, then they are unusable. I enhanced a few by hand, spending a couple of hours 'spotting' out the dust marks using the cloning tool. Then I decided to look for a software fix. Previously I've mentioned Digital Ice, which is included with the software on many scanners. The trouble is it is designed to work at the scanning stage and isn't intended to be sold separately. And then I found the Photoshop Polaroid Dust and Scratch Removal. It can be downloaded for free from the Polaroid website. It's an amazing tool, but using it effectively isn't necessarily straightforward. Look at the Masterclass (further down this page) to find out how I removed dust and scratches from a variety of images.

QUESTION TWO
They say that in dull winter months you can still take good photos by concentrating on black and white, but I'm not so sure. Are there any techniques to brighten up colour photos taken in dull weather? What about replacing a blue sky with a cloudy one?
Shane Coggin

Many photographs taken in overcast weather can look disappointingly gloomy and dull when viewed on screen. You might be tempted to bin them, but believe me they can be improved. The reason why photos taken in cloudy weather look unappealing to the eye is the low level of contrast, that's to say the difference in brightness between the brightest and the darkest parts of the scene. Digital cameras are configured to give good results with contrast levels typical for sunny weather. When the sun goes in, the level of contrast reduces, making for a less punchy image. If only you could increase the contrast - Well you can! The only problem is that increasing the contrast in the mid-tones tends to burn out the whites. The answer is simple - make two copies of the picture on different layers, work on them separately adjusting for the contrast in the mid-tones and in the sky, then combine them using the eraser. I use this technique all the time to give more 'oomph', i.e. contrast, to images shot in dull light.

The first picture taken in cloudy weather on Dublin's Quays is dull. I normally shoot slightly underexposed to avoid burn out of white, a common problem on digital cameras.

An easy way to lighten everything using the Levels control is to drag the slider to the left, turning the lightest grey to white and adjusting all other tones accordingly. It looks brighter but the white areas have burnt out.

The solution is to lighten a second copy of the original file, but not as much. With two versions on layers one on top of the other, delete only whitest areas, revealing the more moderately lightened version underneath.

Merge the two layers and you now have a version of the same image but with the tones much lighter and with more contrast.

QUESTION THREE
I've always wanted to capture good sunsets/sunrises, but I've been disappointed with my results so far. In the winter time when the sun is setting as a dark red ball to the naked eye, it always comes out wishy-washy pink in my shots. I've tried stopping down, but then everything just gets murky. Any tips?

Gwynne Penny

AIDAN'S ANSWER
Shooting sunsets can be difficult, the main reason being the high contrast between the the sun and the surrounding sky, and the difficulty in rendering colours correctly. The camera's metering system is set for average conditions. Sunsets often fool the system which can overexpose, leading to pale washed out colours and a sun which is burned out and spills into the surrounding areas of tone.

To avoid contrast problems, it's best to wait until the sunset is well advanced, when the brightness of the sun is weak, with a more even spread of tones. When you come to shoot the sunset, the easiest and more effective way to arrive at the best exposure level is simply to try a variety of exposures, look at the LCD screen and choose the best one. It may well be better to underexpose rather than overexpose. Here are some sunsets taken in a land of spectacular sunsets, the United Arab Emirates.

A typical example of a difficult sunset - Even though the sun is only just above the horizon, it is very bright as the atmosphere is clear. Light is spilling out, causing poor definition of the disk of the sun, and lens flare. The exposure was 1/160 at f7.9

This was easy to photograph, as the sun was low in the sky and reduced to a white disk by dust in the atmosphere. There is not a huge amount of contrast difference between the sun and the surrounding tones.

This image presents problems. Even though the sun is close to the line of the mountains it is still very bright. We have lost the definition of the disk. The sky is a pale orange - just about right. Exposure was 1/260 sec at f8.9

I have reduced the exposure bias to minus two, so the exposure is now 1/568 sec at f 11.1. The sun is now clearly defined, but we have lost the attractive orange colour in the sky. What can we do?

Cheat! If the colour doesn't look right, add colour, as I've done here. The original tone of this image was similar to C. I filled a layer with orange and set it to 'Overlay'. Note that rays of the sun, which is hidden behind the mosque are extremely bright and have caused a giant halo effect which here is very effective.

Cheating can be taken even further by combining two images into one, as here. I've placed the sun above the tanker. Both shots looking out over the Gulf were taken at almost the same time. the sun is very weak and causes no exposure problems. I applied some pink to the lower half of the picture with the tanker to make it match the upper half with the sun.

Here I've combined three pictures into one, the two mosques and the water tower to make a composite sunset image. You can take any building or tower taken by day, place it on a sunset background darken it to make a silhouette. I've applied some orange to the original image, but tried to keep it subtle.

QUESTION FOUR
I am in the process of trying to set up a photo library and would love some recommendations on what software to use. I need something that I can put a fair bit of description in about the photos (place, subject, etc) as it will be for use by other people as well as myself.
If anyone can help by recommending software it would help me a lot. Appreciate any feedback on different software and systems in use.
Thanks!
Sally Jelbert Forum> Software> Photo Library

AIDAN'S ANSWER
If you're thinking of a shared system, then I think it would be worth considering an online solution. Even if it is only to be accessed by a small number of people for the moment, it's nice to be able to view it from any computer, e.g. at home or anywhere in the world. For a long time I wrestled with the problem of presenting my photos and accompanying writing online. I found there was no solution available which met my requirements. In the end I decided to design my own, working with a database programmer. Combining my aims and objectives with his programming abilities, we came up with a system which enables me to store and present photographs and accompanying text online. The material is arranged in categories and subcategories. Clicking on any category or subcategory produces a set of results pages with medium sized picture on the left and text on the right. A larger size picture appears in a popup window. There's a data sheet with keyword and other info. There are extensive search capabilities so you can view results pages on your chosen subject. You can view the system in action by going to my website www.aidan.co.uk.

QUESTION FIVE

Xray Machines and microdrives

Some time ago you answered a query about Xd cards and airport X-ray devices. You replied that the card and the camera would be safe because they worked electronically. I understand that XD, CF and the others are "static" memory and this is why they are unaffected by the X-ray. But what about the IBM Microdrive, which is a small hard disk? I'm also planning to travel with a portable memory storage device, which has a 40gig internal hard drive. Is it safe to allow the hard drive and the microdrive through the X-ray device? I believe laptop computers shouldn't be x-rayed because of the hard drive, so does the same apply here?

Many thanks.

E Woodward

AIDAN'S ANSWER

My answer is the same as the previous one about memory cards: There should be no problem whatsoever having your hard drives scanned by an airport scanner. If they were that susceptible to electromagnetic radiation you would probably have had interference from your mobile phone, tv or other device by now. Though extremely miniaturised, with many moving parts, today's hard drives are remarkably robust and stable. I've put my laptop computers through airport scanners many times and have had no problems. At many airports I don't think they would allow you not to put the electronic equipment through the scanner. At Dublin Airport laptops have to be taken out of bags and scanned separately. Viruses, worms and badly designed software packages pose a much bigger threat to your portable storage devices than airport scanners!

QUESTION SIX

I followed the PS Elements video workshop and removed red-eye from an image. The original file downloaded from the camera was 1.07Mb, but the new (no red-eye) .psd file is 27.8Mb!! Is this usual? Am I doing something wrong? What format/resolution I should choose? I've purchased a 1Gb compact flash, to compliment the 256Mb xD card that was supplied with the camera. This will give me about 80 shots in TIFF, 160 in RAW. Which should I use TIFF or RAW? I intend to store my images on CD-R or, DVD-R/DVD+R and use an album software to manage them Is this a good method?

Happy shooting..

Regards

Steve Ellis

AIDAN'S ANSWER

If I saved all my photos as Tiff Raw or Photoshop files, I would by now have thousands of terabytes of data and a house full of CD's and DVD's and assorted external storage devices. The simple advice is to save as JPEG max. There is some loss of quality but it happens at pixel level and should not be visible to the naked eye. The file will take up no more than a couple of megabytes, or less, easier for storage and for transfer via email. So what should you use TIFF or RAW for? If the camera is set to output these files then by all means save the back to that format if you've not finished editing them or if it's a very special or valuable photograph you'd like to store in the original format at the very highest quality. But for most purposes, JPEG max should be fine. As for the best storage medium, I have recommended CD's and DVD's in the past, but there is a problem with DVD's due to the variety of formats and lack of compatibility. They also take a long time to burn. If you need to save and access your files frequently, then a very large capacity external hard drive may be the best solution.

MASTERCLASS

This is the result of my scan of a 35mm transparency of the Liverpool to Dublin ferry arriving in Dublin in May 1981. The Kodachrome has retained its original colour balance extremely well, but due to the effects of time, the film is covered in tiny specks of dust, scratches and strange spiderly shaped marks. An hour or two of careful work with the cloning tool should be enough to clean up this image, but there is another, quicker way!

With Polaroid Dust and Scratch Removal, two hours meticulous work by a skilled Photoshop artist is done in a few seconds. A preview window appears showing how the image will look after the filter has done its work. There are various controls, full details of which are in the manual, but for now let's use the default settings.

Hey presto! All but the largest dust marks and scratches have miraculously disappeared, but the filter has done some strange things to other elements of the image. It has removed some of the portholes and most of the masts and aerials. How can we control the effect of the filter so that it only removes the things we want it to remove? There's a simple answer: Layers!

We'll copy the cleaned up image into the clipboard, revert to the original, then paste the cleaned up file onto a layer above it. Setting the delete tool to a very small brush, we carefully delete through the cleaned up layer to reveal the portholes and masts on the original image underneath. Nearly all the dust and scratch marks remain hidden. Then we merge all layers.

Finally we go over the file to remove any larger marks the filter has missed and make any remaining changes. We finish up with a near perfect image which just a few minutes ago was a dusty mess. The car ferry MV Connacht has long since been scrapped, but its image lives on spotlessly, thanks to Polaroid Dust and Scratches Removal.

You'll find Polaroid Dust and Scratch Removal at www.versiontracker.com Just enter 'Dust' in the search field.

QUESTION SEVEN

I bought a ND x4 filter for my Nikon D100. However, I am confused. Do I just put the filter on the lens, and leave it to programme Auto or make a note of the settings the camera chooses (w/out filter) then add filter and swap to Manual or do I leave the settings to the camera and increase +1EV?

First of all we need to think about what a neutral density filter does and why we would use one. A neutral density filter reduces the overall brightness levels entering the camera. Rather like a pair of sunglasses, it reduces glare, but once your eyes have adjusted to the lower intensity of light, the scene should appear the same as if the sun wasn't so bright. Most digital cameras are able to regulate the amount of light entering the camera, so why use a neutral density filter? Perhaps the sunlight or flash conditions are so bright that they are more than the camera can handle, even at the smallest aperture setting. You might want to use a wider aperture to focus attention on the subject and throw the background out of focus, or a longer shutter speed to create motion blur. So bearing this in mind, do you make adjustments to the camera when using the filter? No, you don't as you would partially or fully cancel out the effect of the filter. All it is doing is reducing the amount of light entering the camera so leave it to do its job and the camera will do the rest.

QUESTION EIGHT

How do 'F' numbers relate to the old " film " cameras? I think most digital cameras have a range from f2 to around f8, whereas film cameras went up to around f22. I appreciate that f8 is probably equivalent to f22 on film. But why is it I still read in digital photo books and magazines advice to take pictures at f22 for great depth of field. I don't know a digital camera that has those high numbers. Or am I wrong?

Brian Waugh

You've touched on a fundamental optical principle here, and one of the trickest to get your head around. I'll just give a few thoughts and guidelines. Digital SLR cameras - the ones with interchangeable lenses - do have those high f numbers, but most compact digital cameras only go up to f8. The f number describes the amount of light passing through the lens. Think of them as being similar to fractions: When the lens is stopped down to f8, only one eighth of the light is getting through, similarly for f22 or for f2.8. The smaller the aperture, the greater the sharpness and depth of field. The larger the sensor or film size, the longer the focal length and the smaller the aperture has to be. Old fashioned large format 10x8 inch cameras (80 square inches) require f64 or even f128 to get reasonable sharpness or depth of field. Present-day compact digital cameras with their 'micro-format' sensor (smaller than one square inch) need only a moderately small aperture. The charactistics of the different formats are quite different, so you can't really talk about equivalents. To find out more, go to the Digital Camera Magazine Forum, and see also the 'On The Forums' from

WHERE CAN I FIND OUT MORE ABOUT

Where can I find out more about... Depth of Field

You'll find a highly technical and very thorough explanation of the principles of Depth of Field on the website of US-resident Polish physicist and software developer Andrzej Wrotniak. Incidentally his photo gallery contains excellent digitally-captured images that put many a professional photographer to shame.

http://www.wrotniak.net/photo/dof/

RECOMMENDED READING

www.digit-all-cameras.com
www.digit-all-cameras-info.com

Two websites produced apparently by the same organisation based in Plano Texas, they provide an interesting case-study on what's good and what's not in digital photography websites. Both crammed to bursting point with text, some of it common to both websites, they give ratings, reviews and price comparisons of digital cameras, as well as background info on digital photography. Glossary explanations are original but camera descriptions are taken straight from press releases. And on the technical pages there are words but no diagrams. Websites such as these demonstrate the superior layout, quality of information and general production values of my favourite digital photography resource website Phil Askey's legendary www.dpreview.com (featured previously in Q&A / Hotline pages)

Find out more about Digital Camera Magazine at the website www.dcmag.co.uk

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Below is the original text plus images submitted for the Hotline Question and Answer 4 page spread Digital Camera Magazine Issue number 15, December 2003.

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