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)

I recently posted the query below to the Nikon Discussion List (a list with quite a number of experienced Nikon users; the list offers email, web or RSS interfaces):

I tried searching for this with no luck. After reviewing the manuals for my Nikon gear (D200 & 8800) and some experimenting I am just looking for confirmation.

Based on the manuals, if you select many of the in-camera image ‘optimization’ (i.e. D200 Optimize image: Normal, softer, vivid, more vivid, custom,etc.) settings (at least for the camera models above) then the in-camera enhancements are limited by file types - I am looking for confirmation that:

- RAW files - are *never* tweaked/adjusted by such settings? (i.e. .NEF files are always ~equivalent to film negatives – simply reflecting basiccamera settings from the capture, ie.. ISO, shutter, aperture, WB, etc.)

- does the JPEG embedded preview embedded in the RAW file reflect ‘optimized’ settings?

- only JPEG/Tiff/other? file types are affected by such settings?

- something else/additional info on this?

For many photo sessions I will shoot RAW+JPEG (currently using ALR, CSx/Bridge.) I have seen web postings that indicate that only Nikon software will properly render these optimizations from RAW files?

===

My summary from the responses (which confirmed what I thought about Nikon NEF/JPEG generated files):

1) NEF (RAW) Nikon files are not directly affected by in-camera optimization settings (at least for relatively recent Digital cameras from Nikon.)

2) JPEG images do reflect in-camera ‘enhancement’ options (saturation, hue, sharpness, other image ‘quality’ options that you can configure using camera settings); the in-camera processing will apply these changes as the files are saved to storage.

3) A guess – each NEF (RAW) file includes an embedded JPEG preview image – I am guessing that this embedded image also reflects optimized settings – can anyone confirm?

Also, for standard camera settings, NEFS & JPEGS contain the same EXIF data for ISO, aperture, shutter speed, etc.

If you shoot ‘optimized JPEG’ + RAW then you may get ‘double goodness’ – at least that’s how I see it; I can have a very close to ready-to-use JPEG without too much editing and the the RAW file is available if needed. Note that the options for RAW+JPEG may vary between camera models – in some instances you have to choose between RAW or optimized JPEG (i.e. older model Coolpix like the 8800.)

An additional note – I previuosly found that some image editing software will alter RAW files (i.e. tinker with your negative!) and this includes prior versions of Nikon software – which would update the embedded JPEG in NEF files (not sure if current versions do this); just something to consider before you start editing your RAW files.   Newer versions of digital photo editing software tend to treat (or give you an option to treat) your RAW or JPEG files as negatives – no changes are made to the file; instead instruction ’sets’ are created and a new image is ‘rendered’ by the software (i.e. Adobe Lightroom 2 and Adobe Photoshop CS4.)   If there is any doubt about this or if you are concerned about having your negatives auto-adjusted then simply create a backup BEFORE doing any editing.   If you use some of the auto-import features then there is also a chance that these tools may be altering your negatives…

Note that when you print an image you are NOT printing the RAW (.nef) file – you are printing an image that your software converts from the RAW format to either JPEG or some other, non-RAW format (i.e. .PSD, .TIFF, .BMP, etc.)  You may also be interested in my post about ink-jet Photo Printing using Adobe products.

Metadata or Meta-data is data (information) about data (in this case, image files.)  Modern digital cameras (as well as other digital recording devices) usually store technical information within files created by the device (i.e. digital cameras or cam-corders.)  The ‘native’ information is typically related to the creation of the files captured by the device (i.e. for a digital camera, the date, time, and exposure settings for an image at the time of capture – dates will reflect the internal settings of the camera so they may not be accurate.)  For a digital camera, this data is typically referred to as EXIF data.

Exchangeable Image File Format (EXIF)

Exchangeable Image File Format (EXIF) is a part of the file structure commonly used for image storage.  It has become a standard within the JPEG (and other) common image file formats.  EXIF data may include all of the data types listed below as well as other data specific to a manufacturer’s equipment:

• Device Make and Model
• Date and time of capture
• Shutter Speed
• Special device-specific settings (i.e. program modes)
• F-Stop and Aperture values
• ISO setting
• Focal length of lens
• Flash information
• Type of metering used
• Pixel dimensions and image orientation (i.e. portrait or landscape)
• GPS coordinates (either from a built-in, externally attached GPS device or added during post-processing)
• Colorspace and light source information
• other manufactuer specific image information
• custom data (configured within the device, i.e. an embedded copyright statement)

All of the above data can be quite helpful when reviewing images – which camera settings work ‘best’ for the captured scene types?  what are the limits for this camera? (which settings border on the limits of what can be done with the device? creating a sequential/time-based slide show, etc.)

Other data

Other types of data are typically added during the post-processing of the files.  For instance, as a photographer I will add contact information, descriptive information about the scene including location and events as appropriate, rights management information (for viewers interested in commercial use of images), and other appropriate information.  New operatings systems now provide relatively easy viewing of some of this information (i.e. using the Windows/Vista File Explorer and ‘turning on’ the extended attributes tabs.)

Editing Photo Metadata

Using tools like Adobe Lightroom, Adobe Bridge and other programs you can edit (or remove this information from your image files.)  You should consider including basic contact information that you release in electronic form – in some case, web photo-sharing sites will add/edit this information when you upload images; in all cases I suggest that you include copyright information for images that are distributed via digital means (web pages, CD/DVD or other media.)

Meta-data tools for Linux – ImageMagick

OVERVIEW
ImageMagick®, is a software suite to create, edit, and compose bitmap images. It can read, convert and write images in a variety of formats (about 100) including GIF, JPEG, JPEG-2000, PNG, PDF, PhotoCD, TIFF, and DPX. Use ImageMagick to translate, flip, mirror, rotate, scale, shear and transform images, adjust image colors, apply various special effects, or draw text, lines, polygons, ellipses and B\[’e]zier curves.

ImageMagick is free software delivered as a ready-to-run binary distribution or as source code that you can freely use, copy, modify, and distribute. Its license is compatible with the GPL. It runs on all major operating systems.

ImageMagick is primarily a set of command line tools (but there are several GUI interfaces) which provide the means for converting, adjusting and pulling information out of digital image files.

Note that this image information is flagged with ‘rights managment’ in the sample output below using the (Linux/ImageMagick) identify command:

identify -verbose sara-test.jpg

Image: sarah_6264-0806-2008.jpg
Format: JPEG (Joint Photographic Experts Group JFIF format)
Class: DirectClass
Geometry: 3300×2550+0+0
Type: TrueColor
Endianess: Undefined
Colorspace: RGB
Depth: 8-bit
Channel depth:
Red: 8-bit
Green: 8-bit
Blue: 8-bit
Channel statistics:
Red:
Min: 0 (0)
Max: 255 (1)
Mean: 135.414 (0.531036)
Standard deviation: 75.4208 (0.295768)
Green:
Min: 0 (0)
Max: 255 (1)
Mean: 138.12 (0.541646)
Standard deviation: 68.4699 (0.26851)
Blue:
Min: 0 (0)
Max: 255 (1)
Mean: 116.812 (0.458087)
Standard deviation: 80.3365 (0.315045)
Rendering intent: Undefined
Resolution: 300×300
Units: PixelsPerInch
Filesize: 4.99105mb
Interlace: None
Background color: white
Border color: rgb(223,223,223)
Matte color: grey74
Transparent color: black
Page geometry: 3300×2550+0+0
Dispose: Undefined
Iterations: 0
Compression: JPEG
Quality: 99
Orientation: Undefined
Properties:
Exif:ResolutionUnit: 2
Exif:XResolution: 300/1
Exif:YResolution: 300/1
Jpeg:colorspace: 2
Jpeg:sampling-factor: 1×1,1×1,1×1
Photoshop:LegacyIPTCDigest: C95D651F1F7312FDDF1C37B595F55829
Rdf:about:
Signature: e18c62be76d4448795f825acc7547e55a7879581bedcd0396a0f3bf3ca9341ca
Tiff:Orientation: 1
XapRights:Marked: True
XapRights:WebStatement: DER_08062008_6264_forsyth_fount_scb: http://www.dalereagan.com/

Xmlns:dc: http://purl.org/dc/elements/1.1/
Xmlns:photoshop: http://ns.adobe.com/photoshop/1.0/
Xmlns:tiff: http://ns.adobe.com/tiff/1.0/
Xmlns:xapRights: http://ns.adobe.com/xap/1.0/rights/
Profiles:
Profile-8bim: 126 bytes
Profile-exif: 72 bytes
Profile-icc: 3144 bytes
IEC 61966-2.1 Default RGB colour space – sRGB
Profile-xmp: 2962 bytes
Artifacts:
Verbose: true
Tainted: False
User time: 0.540u
Elapsed time: 0:02
Pixels per second: 8.02517mb
Version: ImageMagick 6.3.8 04/23/08 Q16 http://www.imagemagick.org

If you are a digital photographer in Savannah and need assistance with your gear then please note that I do offer one-on-one training – please use the contact form on this site to request more information.