Strange stripes

[rsfoto]

I am scanning on a Polaroid SprintScan 4000 with Silverfast v5.5.1r08 as well as with Polacolor Insight 5.0 and I get some strange stripes on the Silverfast result.(see sample photo below)

If I compare the scanning behaviour between the 2 software?s I can see that Silverfast moves in small steps forwards and backwards, I guess the software is sampling the same piece of slide several times and Polacolor goes through in one single movement.

<img src=http://rainerehlert.com/silpol.jpg>

What could cause this problem and who has the same problem?


_________________
Rainer Ehlert
RS Fotografia

<font size=-1>[ This Message was edited by: rsfoto on 2002-02-05 01:04 ]</font>

[LSI_Flyvbjerg]

The bahviour of SilverFast (moving forward and backward in small steps) can be normal, if you use the highest resolution (4000 dpi) and if you are scanning negatives. For negatives, SilverFast scans 16-bit raw data, where Polaroid Insight possibly only scans 8-bit. SilverFast then scan more data than Polaroid Insight and is not able to process the data fast enough, so the scanner goes into start / stop mode. Anyway the stripes shouldn?t be there. Is there also the color difference that you showed in your images (magenta and green)?

[rsfoto]

Hi Eric,

Do not bother about the colors. That is not the problem.

The polaroid scan is also 16bit depth so the amount of information is the same.

I started everything from scratch. Deleted Silverfast completely an reinstalled it from the v5.0 and went up to the last v5.5...

Everytime inbetween I made a comparison scan and surprisingly the best scan, but also with stripes, was in the old version 5.0.

I am exclusively scanning slides.

I already reported this problem about 4-5 months ago directly to Silverfast but they stay in silence.

The only explanation for me is the multiple scanning of the slide and here is where Silverfast has the problem.

A pity that one is not able to choose between mutiple sampling or not.

Well, I thing I have to live with it and continue scanning the difficult slides with the Polacolor Insight software from Polaroid and the easy ones with Silverfast or take another decision.

By the way. I have to scan at highest resolution to be able to resize in Photoshop. I made a trial in scanning at low resolution and choose final output sizes and the result was awful. The upsizing during the scan is not good with Silverfast. It is far better in Adobe Photoshop.

For example scanning at 100% at 4000dpi gives a better result than scanning at 300dpi and upsize it to 1333.33%. Theoretically the result should be the same but it is not.
_________________
Rainer Ehlert
RS Fotografia

<font size=-1>[ This Message was edited by: rsfoto on 2002-02-07 22:04 ]</font>

[rsfoto]

.....SilverFast then scan more data than Polaroid Insight and is not able to process the data fast enough, so the scanner goes into start / stop mode.......

I just read this again and I am really surprised that you admit that Silverfast is not fast enough to process the data received during the scanning process.

I do not understand this.

There is the implementation of multiple pass scanning and Silverfast is not able to deal with the data ????? Is it then not a problem of the software of transferring the file to the disk? or is it the SCSI Adapter?

I am working on a AMD Athlon 1.4 GigaHertz speed with 1 GigaByte RAM. My harddisk are all 100?s.

Should I try a faster SCSI adapter? Would this solve my problem ?. I have no problem buying one, but if the problem is not solved with this, then what?

[ilyons]

For example scanning at 100% at 4000dpi gives a better result than scanning at 300dpi and upsize it to 1333.33%. Theoretically the result should be the same but it is not.

FORGET theory - scan at 4000ppi as doing so means NO interpolation, no buggering around. Do you rescaling in Photoshop as a LAST step and not at the beginning.

I just read this again and I am really surprised that you admit that Silverfast is not fast enough to process the data received during the scanning process.

I do not understand this.

It should be fairly clear what the difference is - Silverfast delivers the final scan into Photoshop almost instantly whereas PolaColor takes ages to process the scan before output to Photoshop.

There is the implementation of multiple pass scanning and Silverfast is not able to deal with the data ????? Is it then not a problem of the software of transferring the file to the disk? or is it the SCSI Adapter?

I am working on a AMD Athlon 1.4 GigaHertz speed with 1 GigaByte RAM. My harddisk are all 100?s.

Should I try a faster SCSI adapter? Would this solve my problem ?. I have no problem buying one, but if the problem is not solved with this, then what?

The problem with multi scan is NOT your computer, memory or anything to do with SCSI - the simple truth is the scanner isn't capable of aligning the image in the same precise location on each traverse of the slide.

One thing you might try is to uncheck the Limit Gamma Slope in the Options>Special tab. This will ensure that the shadow end data isn't clipped and so "might" help reduce the banding effect you see. No Promises!!!

IanL

<font size=-1>[ This Message was edited by: ilyons on 2002-02-08 01:24 ]</font>

<font size=-1>[ This Message was edited by: ilyons on 2002-02-08 01:27 ]</font>

[rsfoto]

Hi Ian,

Thanks for your reply. One question!

What would we do without you ???

After reading your post I ran some tests. By unchecking the Limit Gamma Slope the scan improved quite something but the stripes are still slightly there.

Also the scan quality is far better.

You convinced me to stay with Silverfast.

I will not argue about scanning times because this is no issue for me. Important is the scan quality. By the way just for your info and making the test both with 16bit depth: the polacolor is faster even if you say that it takes ages. Polacolor made the scan in ~1' 21" and Silverfast in 2' 25", but as I said this is no discussion point.

I want quality and not speed. If I want speed I take my little Polaroid SprintScan 35 LE for the archive scan.

Ian, Thank You again. I think a lot of people here appreciate your help especially that your advises help us.


_________________
Rainer Ehlert
RS Fotografia

<font size=-1>[ This Message was edited by: rsfoto on 2002-02-08 03:44 ]</font>

[calvorn]

I have the same "stripes" problem with my SprintScan 120. It is most pronounced with 6 x 7 transparencies. I shoot Velvia and rate it at ISO 40. The stripes are most obvious in the darker areas. When you look at individual channels the strips are most pronounced in the Red and Green channels. I have "Limit Gamma Slope" unchecked and I scan at 4000 dpi. I tried a hi bit scan for comparison and it has the same problem. I don't see the stripes in lighter,less saturated images. The scan looks like someone took a dirty squeegee and ran it across the transparency but the film is very clean and dust free. Anybody got any other suggestions?

Thanks.

Cal

[davidgordon]

I've had something like this on my SS4000. Only in bright areas such as the sky. I see strips when darkening the sky.

But some days it's not there...

I think it's a SCSI issue. Double check all connections and terminators. Don't trust the built in termination!

[rsfoto]

Hi Gordon,

well I tried everything and I finally got rid of these strange stripes.

on OPTION > AUTO I set everything to 0. Even on the PIP I set 0 and on shadows I left it on 100.

Take a look at the screenshot here:

http://rainerehlert.com/sf.jpg