This tutorial is one of many instructional videos
presented by Olympus Industrial Equipment.
This tutorial will provide you with detailed instructions
on high dynamic range imaging
within the Olympus Stream image-analysis software.
Many industrial samples contain both bright, highly reflective features,
as well as dark, less reflective features in the same field.
This can present challenges when it comes to digital imaging.
When the exposure time is set high
to display detail on dark features,
reflective features become overexposed,
resulting in loss of surface detail.
Conversely, if the exposure time is decreased
to avoid glare on reflective features,
dark features are underexposed and surface detail suffers as a result.
To overcome this challenge, OLYMPUS Stream
offers a "High Dynamic Range" imaging option.
By capturing a series of images at varying exposure times,
then applying an appropriate tone-mapping algorithm,
the resulting composite image is composed of ultra-high contrast
and excellent surface detail on every feature,
regardless of its reflectivity.
This technique is best applied on samples
containing inherently high and low reflectivity.
To begin, activate the camera’s live mode and choose manual exposure.
Then, focus on the sample.
Check the "Activate HDR" box.
Once HDR has been activated, you will notice
the former "snap" button transform into the "HDR" button.
The exposure range must now be determined for HDR acquisition.
The exposure range will determine both the highest exposure time
for displaying detail on dark features,
as well as lowest exposure time for displaying detail on bright features.
The exposure range can be determined either automatically,
prioritizing convenience, or manually,
for a greater degree of process control.
To determine the exposure range automatically,
press the "automatically" button.
After a few seconds, the exposure range is set.
To determine the exposure range manually, press the "manually" button.
Following the on-screen instructions, adjust the exposure time
to show sufficient detail on the bright features
without overexposing any part of the image.
Then, click "OK."
Next, adjust the exposure time to show sufficient detail
on the dark features without being underexposed.
Then, click "OK."
Because a high dynamic range image contains more colors
than can be displayed on the monitor,
a tone mapping algorithm must be applied.
To choose an appropriate tone mapping algorithm,
click the "Acquisition Settings" button.
From the "Acquisition" menu, choose the HDR sub menu.
From here, you can select an appropriate "Output rendering"
or tone mapping algorithm.
Each tone mapping algorithm accentuates image detail differently,
and can be chosen depending on which features of interest
you wish to highlight.
A detailed definition of each algorithm
can be found in the online help,
accessible by clicking the question mark button.
Please note that when performing tasks
where pixel intensity is measured, such as image-analysis,
only the "Linear" tone mapping algorithm is recommended.
The exposure range increase, determined earlier,
is automatically calculated and displayed in this window,
but can be changed if desired.
This number denotes the factor by which
the current exposure time is multiplied by
to calculate the exposure range.
For example, a 4ms exposure time and 3x exposure range increase
will result in a 12ms exposure range.
The number of frames to be acquired during the HDR acquisition
is automatically calculated and displayed in this window.
A wide exposure range will require more frames,
whereas a short exposure range will require less frames.
This value can also be changed manually if desired.
Choosing the option "Auto Contrast After HDR"
automatically adjusts the image scaling after acquisition,
further optimizing contrast.
Choosing the "Automatic HDR Preview" option
will display a preview of the HDR image immediately
after the exposure range is determined.
This way, you can conveniently decide if your exposure range
is satisfactory or requires further adjustment, before acquiring an image.
The "Preview Snapshot" button is only recommended
when Stream is configured to archive images into the database
or specified folder, automatically after acquisition.
By previewing the HDR image, the operator
is not required to take the additional step of deleting the saved image,
should they be unsatisfied with the results.
After all the acquisition parameters have been defined,
click the "HDR" button to acquire the image.
HDR image acquisition is now complete.
As you can see, the HDR image displays
a high level of detail on both bright and dark features,
with an unprecedented level of contrast.
High Dynamic Range imaging is also supported by the Process Manager,
and is available with tools such as EFI, MIA and Time-Lapse Imaging.
Once the HDR option is checked in the Camera Control tool window,
it is activated in the Process Manager.
In this instructional video, we have covered high dynamic range imaging
with Olympus Stream imageanalysis software.
We hope this video has been beneficial,
and we invite you to contact us directly with any questions.