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File size difference with Vuescan vs. Silverfast

Evan Bedford , Nov 20, 2008; 11:01 p.m.

I'm wondering why my Silverfast scan file results are approximately twice the size of my Vuescan files. I scan both with the same dpi and the same 24 bit color, and when I double check the results in an image editor, the file info shows the same number of pixels in the width and height and the same color depth. They're both TIFF files, but even when I save the Silverfast file as a BMP and as a different named file, the file size is still double.

When I multiply out the horizontal and vertical pixel numbers, the vuescan file is right on the money with regard to file size. Also, the bundled Epson scanning software that came with the V700 gives the same file sizes as the Vuescan software, so I'm thinking something is out of whack with my Silverfast settings.

Any thoughts?

Thanks in advance.


Scott M. Knowles , Nov 21, 2008; 08:39 a.m.

Are all the tif files the same size? If they are then nothing wrong, just use the tif file. Why save the file as a bmp, then the difference is the bmp format, which is considerably larger in size due to the data structure, see article. I've never had problems with Silverfast on my V750, and prefer it to the Epson software.

Scott Turner , Nov 21, 2008; 09:08 a.m.

The fact that your size difference is double is probably the best clue. There are really only two possibilities:

1) Are you sure you've got both set to 24 bit (8 bit/channel) color? Vuescan needs to be set properly in two different places. And...

2) Are you sure you're scanning at the same resolution? Setting resolution in Silverfast (and getting what you think you're getting) is amusingly tricky.

I use both applications, and TIFFs from each are exactly the same size, plus or minus minor differences for cropping, given the same bit depth and same resolution.


Mendel Leisk , Nov 21, 2008; 03:15 p.m.

Have you got tiff compression set to "On" or "Auto", in Vuescan's Output Tab?

Scott Turner , Nov 21, 2008; 08:01 p.m.


I doubt that tiff compression would account for a regular 2x difference. In fact, tiff compression will sometimes result in the "compressed" files being larger. Go figure.


Mendel Leisk , Nov 21, 2008; 08:41 p.m.


Hey, I'm grasping at straws ;)

Vuescan's tiff compression was the *only* application I've ever seen where the result *was* smaller, not bigger, as you mentioned. Photoshop tiff compression did nothing *but* increase file sizes, in my experience. All said, I found tiff compression a waste of time, and possibly risky.

Vuescan's tiff compression in my experience, with grainy scans, was maybe 20% improvement. It could be with a smooth file you'd do better.

Ok, another guess, are these all b/w images, only the silverfast one is in rgb format? That would make a 3 fold difference though...

Evan Bedford , Nov 22, 2008; 05:04 p.m.

Scott K, sorry, the bmp was an unintentional red herring. Both files were originally tiff's.

Scott T, and Mendel. Vuescan's fine. It's the silverfast that's giving me double the file size. On the same 2,600 pixel by 2,000 pixel photo, the vuescan file size is 8 megapixels, while the silverfast is 15 megapixels. I know everything's being scanned at the same resolution, because when I zoom into details, the number of pixels showing on a tiny detail are exactly the same.

I've sent a query into silverfast. Hopefully they can shed some light. Thanks anyways.

Evan Bedford , Nov 22, 2008; 05:08 p.m.

Sorry, the bmp was just an attempt to reduce file sizes. All were originally tiff's.

Vuescan's fine. It's the silverfast that is the hog. On an identical scan with an output of 2,600 by 2,000 pixels, the vuescan gives a file of 8 megapixels and the silverfast gives 15 megapixels. And I know the resolution is identical, because when I do an extreme zoom, the number of pixels on a tiny detail are exactly the same.

I'm sending a query into silverfast to see if they can shed any light. Thanks anyways.

Karl-Heinz Zahorsky , Dec 01, 2008; 03:31 p.m.

Dear Evan,
SilverFast saves TIFF-files in uncompressed standard TIFF-Format (24 or 48bit), so files are 100% compatible with most imaging applications. If you want high quality lossless compression, use SilverFast Ai Studio, which supports JPEG 2000, which is also supported by Photoshop as well as by SilverFast HDR Studio.
JPEG 2000 is the best compression supporting up to 16/48bit and can save lossy and lossless at high compression speed!

If you like to know more about the SilverFast resolution concept, which is derived from high end professional scanner, which is helping to easily define the appropriate resolution, you can check out the following tutorials: http://www.silverfast.com/show/tutorials/en.html
Karl-Heinz Zahorsky
President & CEO
LaserSoft Imaging AG http://www.silverfast.com

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