Savannah Photographer Dale Reagan

Deciding on which in-camera file type to save is usually based on your needs and digital image file knowledge.  In a nutshell, RAW files provide more data and provide more options for editing.  If you are working a tough lighting situation then RAW probably a better choice.

Well, what about normal or good lighting scenarios?

• If you need speed then JPEG is *usually* better (it will take less time for your camera to store a JPEG file than a RAW file – this is simply math – RAW files are usually several times larger than corresponding JPEG files; writing less data to a memory card *should* take less time…  A scenario (today, anyway) where JPEG makes sense might be any sport activity with rapid action – you don’t want to be waiting for your camera to save the last image to take that next picture…
• Otherwise, I suggest staying with RAW
• For some cameras you can save both RAW & JPEG (or perhaps other image file formats like TIFF.)  This can be useful if you need both lattitude in development (i.e. from selected RAW images) and faster processing (i.e. from JPEG files; smaller file ~= less time to process for output/delivery.)  Note that this setting consumes storage space RAPIDLY…

Editing your images – some guideline/suggested limits

Ok, you are now back at your computer and making your selects.  Let’s say that you have at least a few images where the exposure was not perfect and you need to make adjustments – how far can you go before your changes start impacting image quality?  It depends on several variables but for this discussion we will assume that you camera is set to the highest quality image that it can produce.  In general, for exposure changes we can adjust:

JPEG  – exposure latitude = < 1 stop

• suggest edit limit of 1/3 stop over OR
• 1/2 stop under exposure

RAW – exposure latitude =  6-8 stops (could be more – depends on image sensor)

• suggest edit limit of 1 stop over/under

Note that you can surely make larger changes than those suggested above – the point is that you want to get your capture to be within easily editable ranges.  So, how can you get your exposure as close to possible to ideal? I suggest:

• taking test pictures and evaluating the histograms (See below) AND/OR
• consider using the bracketing features of your camera (auto-bracketing is a feature where your camera will capture multiple images and vary the exposures based on how you configure the bracketing option.)

Histograms

• scene dependant brightness levels and quantity of pixels in an image
• histograms from RAW files actually display, interpolated JPEG data
• 0  = black, dark side (usually on the left, i.e. dark areas with shadows)
• 255 = brightest, white side (usually on the right,  i.e. the sky)
• a ‘balanced’ histogram is ‘well exposed’
• too light (high values on the right) = contains some under-exposed areas
• too dark (high values on the left) = contains some over-exposed areas
• clipping occurs when ‘detail’ is lost (values on the extreme left or extreme right of the histogram)

Use Calibration TARGET Reference Cards

• white balance via a Gray Card (mid tone 18% gray or other tools)
• whibal.com
• rawworkflow.com
• balancesmarter.com
• photovisionvideo.com

Expose for your SUBJECT (center of histogram)

• single source reference – simple histogram
• multi source reference – i.e. three stripes, white, black gray; where are your high & low key light areas

Using a target

• take picture (with subject holding target or target in scene); fill with target
• evaluate histogram – adjust exposure if histogram leans left or right (i.e. keep Aperture but adjust shutter speed up or down)

Which Statement is True?

A Camera Never Lies… or

A Print is only one possible interpretation of an image…

Both have merit and both have depend upon human and medium variables.  In the old (film) days there (very broadly speaking) were two types of photographers:

1. those who created photos and hired out developing and printing and
2. those that handled print creation from start to finish.

The basic limits of what could be done with a print were tied to the  quality of the original negative image;  the printing process allowed for an additional creative touch to be applied to the final print.  Those photographers who handled all of these steps could of course have maximum creative input into the final output.   It should be noted that most (if not all) aspects of image creation and printing were controlled by the photographer or printer.  The choice of film brand, type, ISO as well as the choice of chemicals and papers used all affect the final outcome and, in  many cases become a type of signature for a photographer or printer.

In the digital photo world these factors are still in play (or they can be.)  Camera manufactures have made tremendous, perhaps even miraculous progress in developing current digital cameras (entry level to pro dSLR systems.)  Photo-printer manufactures have made similar levels of improvements.  It is now possible to click the shutter button, wait a few seconds for the image to pass through the air to your wireless network, reach your computer and then be shuttled to your inkjet printer – all  without you having/needing to decide on any camera settings, computer settings, printer settings, nada!   Provided that your ink levels are good and your photo-printer paper is of reasonable quality you will most likely wind up with a print that is acceptable and it may even be a photo that your share with others.

If you take the ‘no-hands’ approach described above then for each auto setting you use you are actually allowing the camera (i.e. the knowledge/wisdom/skill of the camera, printer, computer & software engineers) to pick for you.  There is nothing wrong with this – it’s just a choice that you make; most serious photographers (pro and non-pro) will make these choices (i.e. they won’t use any automatic settings.)  Does this really make any difference?  So far, no, not much difference – well, not until you start doing truly creative things with the image/print.

Cameras (film or digital) are really, really, really dumb – compared to the combination of the human eye and brain.  The camera will never ’see’ the level of image complexity that we perceive in a scene (our eye/brain combination is a 3d view; a camera only has a 1d, flat view.)   So, a camera never lies really means that a camera never sees the whole truth…  How about:  the print never lies? The camera is much closer to the original image – any print that we encounter is in fact, one interpretation of any given image and as such, is much less likely to be close to any sort of truth – a digital negative (file) is much closer to the truth (errr, the camera’s truth.)

JPEG, TIFF, RAW – the Digital Negative

Camera manufactures offer you choices – most cameras include an option for RAW files.  The choice of digital negative file type impacts image quality and places practical limits on what can be done with your negative.  JPEG  files are cooked – i.e. they are sort of like using other automatic settings – they limit your creative input control.  RAW files allow the most flexibility for post-processing.  A simple example is the choice of light temperature (i.e. setting the camera for daylight, night, cloudy, etc.)

If you have a RAW file then you can change this after the photo has been taken; if you use a JPEG file then you have to re-process the file (i.e. create a new file to use) to fix a problem like this.  Since a RAW file is never a work-file, you could argue that there is no difference.  In addition, the latest version of Adobe Lightroom treats all negative files as if they were RAW files (any changes result in the creation of a new file so the original is never changed.)  If your camera supports it I suggest that you try using a setting that provides you with both a RAW file and and a JPEG file – only then will you be able to see the differences in both types of capture.

NOTE – since I first wrote this many software products have changed – many current products allow you to treat a JPEG file like a RAW file, i.e. any changes are made to a copy of the original file so your ‘negative image‘ is preserved as long as you use software that does not change it…

A brief introduction to the topic of digital workflow:

1. What is digital workflow?

2. Why should camera users care about digital workflow?

3. What is meta-data and why is it important in a digital workflow?

4. Why is the camera image file format important?

5. Why is the backup medium important?  CDs/DVDs will last for hundreds of years, right?

6. What resources can be used to learn more about digital workflow?

1. What is digital workflow?

Digital workflow is the process or sequence of steps that is traversed to move a captured image from a camera to it’s final end use.   Steps along the way can include:

• making a copy of the files on the CF card (or other camera media) to a hard disk or other storage device
• evaluating the images (delete rejects, apply ratings, labels, or other ‘quality’ stamps)
• applying a naming convention to the files (default in-camera file naming conventions are currently fairly limited in that they usually only include a sequence number and some sort of vendor designation along with a file format type for example  the name:  DSCN1038.JPG.)
• applying meta-data to the files (i.e. adding copyright, photographer contact, image description or other information that will make the image data-rich)
• converting captured images to the file format of choice (currently, there is significant debate about the merits and use of vendor camera RAW image formats; for many end users convenience will drive the file format selection – whatever is easiest to use will top the list – anything else will be used when the need arises/dominate)
• creating backup copies of the files for online, off-site or long term storage
• adding data for the new images to a master database or image management tool/system
• processing images use (i.e. preparing versions of the files for web, print or other presentation usage)
• delivering the final image to clients, family or friends (i.e. printing snapshots for the family, sending out a DVD with press ready images, transferring files to clients via electronic means)

2. Why should camera users care about digital workflow?

Digital media immediately increases post-production time – you simply will have more images to screen/select.  If you only take a handful of images then you won’t typically be concerned with organizing how you handle your images.   On  the other hand, if you are now generating several hundred or thousands of images then it can be quite a time saver if you develop your own process for handling images.  How easily can you put your hands on negatives/slides/prints from 5, 10 or 15+ years ago?  Can you generate a list of all images of your family pets? Or a list of all of your ‘best’ images?  How about a list of all images taken in 2002?  A list of all unpublished images?  A list of all published images?

3. What is meta-data and why is it important in a digital workflow?

Meta-data is data about data – All of the information that already exists in your image files and any that you add after you create the file is meta-data; for digitally captured camera files it usually includes EXIF data as well as information that you might add as you edit the file. Why add more information? – simply put, value.   Data (in this case, an image) that is data-enhanced has increased value as long as the quality of the added information is good.  In addition to speeding up file searches (provided you use some indexing tool that takes advantage of meta-data) adding appropriate meta-data to your images decreases the long term maintenance.

4. Why is the backup medium important?  CDs/DVDs will last for hundreds of years, right?

The ‘life expectancy’ of any optical medium is speculative, not proven by the actual passage of time.  In the same manner that slides,  negatives and prints will age (and possibly/most likely deteriorate) today’s CD/DVD ROM discs will also eventually fail or degrade.  The more you use your CD/DVDs and/or the more you expose them to ‘poor’ conditions, the more likely you will encounter disc failures.   The quality of the discs that you use will also affect the real life that you extract from the medium.

5. Why is the camera image file format important?

The image format that is chosen for long term storage of images is what will determine how easily your images may be used in the future. If the vendor formats keep changing (which is what we are seeing from the camera makers) then you have to keep changing your software in order to work with the images.   If you archive your files using an vendor neutral, industry standard file format (i.e.  TIFF or JPEG) then the chances are good that software 20 years from now will be able to read/use the files.  A nice ‘feature’ of film/slides is that you have something physical to work with and from which you can still get high quality images from.

6. What resources can be used to learn more about digital workflow?

The books found here cover workflow for both general and RAW file format uses.

Digital Photography Vocabulary

• meta-data:  data about data
• EXIF: Exchangeable Image File Format – typically includes information generated from your camera when you capture an image; usually includes information like the image exposure settings, ISO information, lens information, etc.  In general it could contain any information that the camera is capable of recording about the image capture process.
• TIFF – Tagged Image File Format – a cross platform image file format; widely supported in current image editing software programs; a ‘lossless’ format; files tend to be large
• JPEG – Joint Photographic Experts Group – an images file format that compresses files by throwing away ‘excess’ data; a ‘lossy’ format; file size depend on JPEG quality levels
• RAW – generally speaking this refers to any vendor specific (i.e. proprietary) file format used to store images.  Most cameras provide file format choices that offer various benefits.  For many professional users the RAW format provided by their camera vendor will be the preferred format due to the amount and quality of data that these file formats support