VueScan: differences between "Image" and "negative" settings

[Frank Kolwicz]

I've spotted a difference in the noise levels when scanning with
VueScan version 8.0.4 set to Input/Media/Image vs I/M/Color Negative
(WinXP, Minolta ScanMultiPro, Photoshop 6).

The noise is especially noticable in the unexposed spaces between the
frames, but is present in all areas. I scanned a 6x7 Kodak Portra 160
NC frame at the scanner's maximum for the film size (3200dpi) as Color
Negative twice and once as Image, then I selected a uniform mid-toned
area of each scan and examined the Histogram for each selection. The
three histogram peaks were a bit different, but the two as Color
Negative were pretty similar, the one done as Image was quite a bit
different from the others.

Some data: the standard deviations for the peaks were 6.85 and 7.09
for the Color Negative vs 4.32 for the Image scan. While this is not a
huge difference, it is for a mid-toned area, not for the darkest parts
of the image and the difference is significant - I can see it on the
screen at around 25% viewing ratio in Photoshop6. I saw similar noise
levels when scanning a full 6x7 frame of unexposed film leader.

Is this to be expected? I find the use of the Image setting somewhat
inconvenient as I often want to work with something near the natural
colors of my scene and Image gives me the un-inverted color negative
and no semblance of where to start for getting back to my original
color starting point. I can, of course, perform the color inversion in
PS6, but it's a hell of a lot simpler to let VueScan do it, if the
image didn't suffer from the increased noise I get.

Thanks for any help,

Frank

 

[Alan Smithee]

I've spotted a difference in the noise levels when scanning with
VueScan version 8.0.4 set to Input/Media/Image vs I/M/Color Negative
(WinXP, Minolta ScanMultiPro, Photoshop 6).

The noise is especially noticable in the unexposed spaces between the
frames, but is present in all areas. I scanned a 6x7 Kodak Portra 160
NC frame at the scanner's maximum for the film size (3200dpi) as Color
Negative twice and once as Image, then I selected a uniform mid-toned
area of each scan and examined the Histogram for each selection. The
three histogram peaks were a bit different, but the two as Color
Negative were pretty similar, the one done as Image was quite a bit
different from the others.

Some data: the standard deviations for the peaks were 6.85 and 7.09
for the Color Negative vs 4.32 for the Image scan. While this is not a
huge difference, it is for a mid-toned area, not for the darkest parts
of the image and the difference is significant - I can see it on the
screen at around 25% viewing ratio in Photoshop6. I saw similar noise
levels when scanning a full 6x7 frame of unexposed film leader.

Is this to be expected? I find the use of the Image setting somewhat
inconvenient as I often want to work with something near the natural
colors of my scene and Image gives me the un-inverted color negative
and no semblance of where to start for getting back to my original
color starting point. I can, of course, perform the color inversion in
PS6, but it's a hell of a lot simpler to let VueScan do it, if the
image didn't suffer from the increased noise I get.

Thanks for any help,

Frank

I though the Image setting was for generic slides rather than Kodachrome.

 

[Erik Krause]

I've spotted a difference in the noise levels when scanning with
VueScan version 8.0.4 set to Input/Media/Image vs I/M/Color Negative
(WinXP, Minolta ScanMultiPro, Photoshop 6).

The noise is especially noticable in the unexposed spaces between the
frames, but is present in all areas. I scanned a 6x7 Kodak Portra 160
NC frame at the scanner's maximum for the film size (3200dpi) as Color
Negative twice and once as Image, then I selected a uniform mid-toned
area of each scan and examined the Histogram for each selection. The
three histogram peaks were a bit different, but the two as Color
Negative were pretty similar, the one done as Image was quite a bit
different from the others.

Some data: the standard deviations for the peaks were 6.85 and 7.09
for the Color Negative vs 4.32 for the Image scan. While this is not a
huge difference, it is for a mid-toned area, not for the darkest parts
of the image and the difference is significant - I can see it on the
screen at around 25% viewing ratio in Photoshop6. I saw similar noise
levels when scanning a full 6x7 frame of unexposed film leader.

Is this to be expected? I find the use of the Image setting somewhat
inconvenient as I often want to work with something near the natural
colors of my scene and Image gives me the un-inverted color negative
and no semblance of where to start for getting back to my original
color starting point. I can, of course, perform the color inversion in
PS6, but it's a hell of a lot simpler to let VueScan do it, if the
image didn't suffer from the increased noise I get.

On scanners that have the feature vuescan increases green and blue CCD
exposure time for negatives. Then it calculates the film base color
from the most transparent area and uses it to subtract the orange mask.
Then the image is inverted and the color balance settings applied.

For image, no film base color ist calculated and subtracted before
color balance is applied.

To simulate the same scanning conditions as for 'Image' but get the
image inverted and color balanced you scan as 'Negative' but lock film
base color (Input tab: Preview, Lock exposure, Preview again) and set
film base color values (on color tab) to 1.0 all. On scanners that can
adjust individual RGB exposure you must scan with image setting to RAW
on disk and with negative setting from disk.

BTW.: I got the impression that I get less grain if I set film base
color values to 1.0, too. But I have the additional benefit of
adjusting individual RGB exposure on my Nikon scanner, and I found a
convenient way to calculate the different exposure values in order to
get an almost neutral scan. I still have to do some direct
comparisons...