User`s guide

VueScan User's Guide
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When the preview or scan is performed, the raw data is put into a memory buffer. If the Output |
Raw file (p. 88) option is enabled and Output | Raw output with (p. 90) is set to "Preview" or
"Scan", the raw data is written to a TIFF file at the same time as it's put into the memory buffer.
Processing
The processing steps are performed for both the preview and the full scan.
The first step uses the infrared data for a first attempt at dust removal (if enabled). This reads
the whole image from the memory buffer to characterize the relationship between the color
channels and the infrared channel. Then it reads each line once, correcting it for dust spots and
passing each line to the subsequent steps for further processing.
The next step is applying the cleaning filter. This filter removes dust spots by using the infrared
data to identify and remove dust spots and then filling in the spots with image data adjacent to
the dust spots. This filter also reduces the appearance of film grain using a sigma filter.
Note: infrared data is only available from scanners that have an IR channel. If the channel is not
present the infrared cleaning options will be skipped.
If saving files, the Output | Raw file (p. 88) option is enabled and Output | Raw output with (p.
90) is set to "Save", the data at this stage is written to a TIFF file. This raw data can
subsequently be re-processed by setting the Input | Source (p. 50) option to "File".
Note: that the data from the infrared channel, if present, is saved as part of the raw file.
Next, the restore colors and restore fading filters are applied (if enabled). This reads the whole
image once to detect the original colors of the image and then reads each line once to correct
for color shifts and dye fading.
The next step is performing corrections for film media. This reads the whole image once to
compute the intensity of the film base, and then reads each line, corrects it based on film
characteristics, and passes each line to the subsequent steps for further processing.
At this point sharpening with an unsharp mask is performed if theFilter | Sharpen (p. 70) option
is enabled.
The last step is color correction. The whole image is read once, and the options from the Color
tab are used to convert to the final colors of the saved images. The inputs to this step are 16-bit
linear light samples, and the outputs from this step are gamma corrected samples.
Once the image data has been corrected, the preview image data is displayed in the Preview
tab or the scan image data is optionally displayed in the Scan tab or written to a TIFF file, a
JPEG file, a PDF file, an OCR text file and/or an index file.
Scanning Color Negative Film
Color negative film is able to capture a much wider range of intensities than slide film, and this
can create a problem when scanning negative film.
Slide film maps a density range of 0:2.7 to an intensity range of 1:500, but negative film maps a
smaller density range of 0:2.4 to a larger intensity range of 1:4000.