Photoshop expert, Terry Steeley's, second tutorial for ePHOTOzine looks at
how to use our digital camera's autobracketing mode to create perfect exposures.
When using Autoexposure Braketing, available on most digital prosumer and professional
cameras, the camera automatically changes the exposure level within the set
range for three successive frames, providing an image at the correct exposure,
one underexposed and one overexposed. This tutorial will show how to combine
the three frames in Photoshop to create one final image. We have also chosen
to capture our images at 16-bits per channel.
This technique is extremely useful when the lighting conditions are tricky
and photographing the right shot is proving difficult. We have provided the
three test images that you can download to use while following this tutorial.
To open click on each of the following links
img_1219.jpg and then right click and select download placing them in an
appropriate location that you can find easily.
Before we begin let's first understand the term 'bit'. 'Bit' depth (also referred
to as pixel or colour depth) measures how much colour information is available
to display or print each pixel in an image. A single bit can store two possible
values - black and white, whereas an 8-bit pixel has 256 possible tonal values
and a pixel with a bit depth of 16 can store up to 65,536 tonal values per channel.
The benefit of capturing and using 16-bit images is simple; when making any
tonal or colour correction changes the amount of detail lost through editing
means that the image after manipulation will still have more tonal values per
channel than if we'd started with an 8-bit file.
8-bit files provide excellent results, but containing only 256 tonal values
per channel it is important that we capture them correctly and minimize the
amount of correction that is required.
16-bit images can only be captured at present with digital cameras set to use
the RAW file format. Unlike the familiar formats TIFF and JPEG that capture
only what the camera sees, RAW files capture much more information than is displayed
by the camera and many options are available to improve the exposure or brightness,
add or remove the sharpening, adjust the image colour temperature and more using
Photoshop's Camera RAW plug-in. Editing files in this way is an opportunity
to perfect the image without losing any detail from the original shot.
1. Using either the 'File Browser' or the 'Open' command, navigate to
the supplied images and open all three.
2. Choose... 'Window' > 'Arrange' and select 'Tile', to organise all
the images to view on the screen side by side. Click onto the image named
'img_1218', this will be our base file, it was captured using the correct
The file named 'img_1217' is the lightest image and 'img_1219' is the
darkest. By combining elements of these two images into the base file,
we will end up with a new image that is completely unlike any of the source
3. Choose... 'Window' and select 'History'. The 'History' palette should
now be visible.
4. Select the lightest file 'img_1217'.
From the 'History' palette, drag and drop the documents 'Snapshot' history
state thumbnail (small image icon at the top of the palette) onto the
base image ('img_1218') document window.
Click onto the base file to see two history states present in the 'History'
5. Double-click on the history state 'img_1217' in the base file and
6. Now, select the image 'img_1219' document window, and drag the documents
'Snapshot' from the 'History' palette onto the base file's document window.
7. Return to the base file and you should now have 3 history states in
the 'History' palette. Double-click on the 'Snapshot' named 'img_1219'
and rename to 'darker'.
History states should be ordered from the top: img_1218, lighter, darker.
8. Close the files 'img_1217' and 'img_1219'.
|9. In the 'History' palette, click on the snapshot 'img_1218'
to load the original state of the image into the document window. The selected
thumbnail is identified with a small marker to the left of the 'Snapshot'.
From the 'Toolbox', select the 'History Brush Tool'. This tool uses a 'Snapshot'
from the 'History' palette as the source when painting. Click to the left
of the 'lighter' thumbnail to activate it as the source for the 'History
Note: There should now be an icon of the 'History Brush' displayed next
to the 'lighter' snapshot. The small marker identifying the 'img_1218' thumbnail
as being displayed in the document window should still be pointing to the
10. The key to making this work successfully is by altering the opacity of
the brush as you paint detail onto the base image. Unless you are using a Wacom
tablet and pen which is pressure sensitive, then I suggest that you use the
keys 1 - 0 along the top of the keyboard to quickly change brush opacity. 1
= 10%, 3 = 30% and 7 = 70%, etc.
With the 'lighter' thumbnail still selected as the source for the 'History Brush',
paint over the lightest areas of the image to lighten them further. You can
also paint over areas that you would like to be lighter.
11. In the 'History' palette, change the source of the 'History Brush' to the
'darker' snapshot. The 'History Brush' icon should be displayed next to the
'darker' snapshot. The small marker should still point to the 'img_1218' snapshot.
12. To emphasize the flower we need to darken the background.
Increase the size of the 'History Brush' using either the 'Brush Options' in
the 'Options' bar or by using the keyboard shortcut right square bracket ']'
and paint over the background.
I have also chosen to reduce the size of the brush and paint over some of the
dark areas of the flower to increase the contrast throughout the image.
13. Click on the small camera icon at the bottom of the 'History' palette to
create a new 'Snapshot' of the finished image. Double-click and rename the new
Finally, click through all snapshots to see how the different versions vary.
The 'Final' image should appear much more dynamic than any of the bracketed
About the Author
more than 12 years' experience working with photographers and their images, Terry
Steeley is recognised as a world-class Photoshop specialist, having for the past
four years represented Adobe as an authoritative speaker at worldwide trade shows
His passion for photography and enthusiasm for sharing his knowledge has led
him to develop his highly-acclaimed courses catering for photographers of all
abilities - from the novice and enthusiast to the amateur or semi-professional.
Terry's relaxed style ensures that people can easily understand and absorb
his knowledge. Covering all aspects of capturing and editing digital images,
his teaching blends traditional film techniques with today's modern digital
equivalents providing essential viewing for all interested in exploring digital
Chris Kitchener - Adobe Systems added:
"One of the most natural and gifted presenters of Adobe Photoshop
the audience never fails to be engaged."
The 'Photoshop4Photographers' seminar is an essential day's training specifically
tailored by photographers, to meet the needs of the novice, enthusiast, amateur
or semi-professional photographer, capturing and editing full colour RGB images
Presented by regular Adobe speaker and Photoshop expert Terry Steeley, you
will learn many invaluable 'must know' photographic techniques used by today's
top professionals as well as learn how to digitally recreate traditional
processes of the darkroom.
- Birmingham Saturday 17th April 2004
- Manchester Sunday 18th April 2004
- Edinburgh 25th April 2004
- London Sunday 9th May 2004
Seminar 10.00am 4.30pm
Hurry! Places are now limited on these. For more details and online booking:
£79.00 per person Adobe a-list members £59.00 per person. All prices
Regrettably, only pre-registered attendees will be given admittance on the day
of the event.