Flatbed scanner settings for HDTV

[zoobie]

Can't seem to find much on this or I've missed it somewhere.

I was wondering if my flatbed scanner set at 300dpi 48-bit is going to be good enuf for display on HDTV and blu-ray.

I'm scanning mostly color postcards that are fairly new and may display them on HDTV in the future.

Are my settings high enough? It goes up to 2400dpi

Thanks

[dphirschler]

You can figure it out yourself. dpi=dots per inch. HDTV is 1920x1080. Measure the post card in inches. Divide 1920 by the horizontal measurement and 1080 by the vertical measurement. For instance a 5x3 card would need to be scanned at 384 dpi (and you'd have to crop slightly vertically).


Darryl

[edDV]

dpi only applies to printers not TV. Convert your thinking to pixels.

dphirschler is on the right track but you need to factor for the following.

1. Widescreen format

2. You will probably want to apply effects to these stills such as zoom, pan, crop, rotation, tilt, etc. to do this effectively at 1920x1080 output you will need the original scanned at far higher resolution.

Good effects interpolators work at 2x, 4x, 8x, 16x, etc filtering. Depending on how far you want to be able to zoom, or how smoothly you want to subpixel pan (e.g. Ken Burns effects), you would need to apply those multiples to your original scan.

2x = ~ 4000x2000 adequate
3x = ~ 6000x3000 better
4x = ~ 8000x4000 great for "Ken Burns" effects at full resolution HDTV
8x = ~ 16k x 8k museum quality for crop + zoom

A high quality 1200dpi home scanner can get close to 6000x3000 masters. 2400dpi optical would be better.

Remember that 8 Megapixel still cams take ~ 2500x2000 pixel images so note that as a reference. My recommendations above would apply to pro level widescreen HDTV targets in "future" not current quality. Today, HDTV production can get away with far less because the TV sets are not yet true 1920x1080p. They are nowhere close.

[edDV]

It goes up to 1200dpi

Thanks

Ignor interpolated specs. Your optical resolution is what counts and that seems to be 300dpi. 300dpi is ok for SDTV but not good enough for HDTV scans. Older 300 dpi scanners had many other "issues" that would show up in HDTV.

[zoobie]

So, what's a good general resolution to use for the typical 6" x 4" postcard to archive for hdtv?

I've found my scanner goes to 2400dpi/48-bit btw...

Thanks

[edDV]

So, what's a good general resolution to use for the typical 6" x 4" postcard to archive for hdtv?

I've found my scanner goes to 2400dpi/48-bit btw...

Thanks

Use your highest "optical" resolution. If that is 300 dpi use that. That will be short of full 1920x1080 resolution but better to let photo or video editing software enlarge it rather than use scanner interpolation. A scanner is sharpest at its native optical resolution.

You should invest in a 1200dpi (optical) or 2400dpi (optical) scanner if you want true "ready for HDTV" archives.

[zoobie]

?

I've found mine goes up to 2400dpi...but at that resolution, I'm arfaid I'd only get a couple of scans per dvd...

Thx

[Raga]

Ignor interpolated specs. Your optical resolution is what counts and that seems to be 300dpi. 300dpi is ok for SDTV but not good enough for HDTV scans. Older 300 dpi scanners had many other "issues" that would show up in HDTV.

Hmm... based on what it's 300dpi? Most semi-modern scanners give at least 600dpi optical. 4"x6" in 600dpi is 2400x3600px, which is plenty enough. That is, unless you want to zoom in and out of course, like edDV suggested.

However if your originals are post cards, I'd say 600dpi already borders overkill, as the original print probably doesn't have that many dots per inch. Scanning photos would be whole other issue.

[TooLFooL]

he never said his scanner is 300 dpi optical, he said it was SET at 300 dpi. with 48 bit color, i'm sure his optical resolution is at least 1200 dpi.

[zoobie]

Yep...I kept saying that. It has option of anywhere from 72 to 2400dpi.
So, if 600dpi is overkill and 300dpi isn't enuf, how about 400 or 500?
Gettin nowhere fast here...

[jtoolman2000]

Just set it so that you get a final image that MEASURES 1280 x 1920 Pixels. Forget about Pixels per inch and anything else. You will need a hight of 1280 pixels and if the length exceeds 1920, you will have to crop it. If it does not, you will have black vertical bars right and left. You will not be able to apply that to vertical cards. In that case the height has to be 1280 and you will have large black bars right and left. Just like when you view regular 4:3 TV in a 16:9 hdtv

[FulciLives]

Yep...I kept saying that. It has option of anywhere from 72 to 2400dpi.
So, if 600dpi is overkill and 300dpi isn't enuf, how about 400 or 500?
Gettin nowhere fast here...

The problem is you don't understand the difference between optical resolution and interpolation. I highly doubt your scanner has an optical resolution of 2400dpi ... most likely that is interpolation.

I believe your standard modern consumer grade flatbed scanner has an optical resolution of either 600dpi or 1200dpi ... anything higher and it is much more expensive that your average consumer bought flatbed scanner.

- John "FulciLives" Coleman

[Alan69]

Yep...I kept saying that. It has option of anywhere from 72 to 2400dpi.
So, if 600dpi is overkill and 300dpi isn't enuf, how about 400 or 500?
Gettin nowhere fast here...

Second that. You've also had people tell you the 2400 is imaginary, so why talk like your scanner really does that? If you like imaginary resolution, why not just scan them at 100x100 and save disc space? Who cares if it's blurry because it's fake data, it has 2400 resolution.

If you want real resolution you're going to have to find a scanner that has actual optical resolution at 1200 or 2400, like people have already mentioned..

If you get a scanner that is asymmetrical (optical 1200 or 2400 one way, 600 or 1200 the other), scan with the right way on the better axis, that way you'll have the most real info for the horizontal on the TV where it'll do the most good.

Alan

[dphirschler]

So, if 600dpi is overkill and 300dpi isn't enuf, how about 400 or 500?
Gettin nowhere fast here...

As I said before, you can calculate it yourself. It's a matter of what size (pixel dimension) you want it to be. Personally, I'd scan it at 600 dpi, crop the junk, resize (down) for final display, then add black when/where needed.

You might even want to do a slight blur (berofe resize) to kill any moire' pattern.


Darryl

[edDV]

Yep...I kept saying that. It has option of anywhere from 72 to 2400dpi.
So, if 600dpi is overkill and 300dpi isn't enuf, how about 400 or 500?
Gettin nowhere fast here...

Stop and listen a second. Every scanner has a printed "Optical" resolution. Consumer models used to come in 300, 600 or 1200 optical resolutions. Some now go higher.

To get best performance from your scan you want to use an interger fraction of your optical resolution. You don't want to interpolate.

Example: 1200 dpi optical resolution scanner

For best results you would select from 1200 dpi, 600dpi (uses every other pixel), 300dpi (uses every 4th pixel), 150dpi, 75 dpi and so on.

We have established above that for a 6"x4" source, your scan sizes would be:

1200dpi - 7200x4800 = (6"x1200 dpi) x (4"x1200 dpi)
600dpi - 3600x2400 = and so on
300dpi - 1800x1200

You want to avoid using scanner pixel interpolation. It will prodice an inferior picture. Photo and video editing software will do a much better job doing the final sizing.

You also want the scan to be large enough so that the picture never needs to be enlarged later in software.

If you want "best quality with crop/zoom capability" that would be 600dpi which is larger than 1920x1080 to allow for some cropping and zoom in photo editing software later. The slideshow or video editing software will size the image down when it comes time to encode or display.

300 dpi (1800x1200) will be the best if you just want to display as is with correct aspect ratio. The HDTV slideshow software will shrink the image down 10% to ~1620x1080 and put a color in the sidebars to allow 1920x1080 output.

Are we beginning to communicate?
Find out the optical resolution of your scanner.

I'm trying to show you the steps to the process. If the source was 5"x7" or any other size, you would need to do these calculations again.

[edDV]

For others wanting a bit more here are some observations.

We should all thank the ASTC and other HDTV pioneers for the return to square pixels for 1920x1080 and 1280x720 resolutions. This also holds constant in both NTSC and PAL areas. **

SDTV calculations are much more difficult because video pixels are not square and differ for 4:3 vs. 16:9 and for NTSC (720x480) vs. PAL (720x576).

For SDTV scans it's far easier to oversize your scan and let the photo or video editing software manage the final downsize to your project format.


** However, with HDV format internally using 1440x1080 we still have to deal with non-square pixels at deeper levels of editing (e.g. for still captures, etc).

[zoobie]

"Find out the optical resolution of your scanner."

I knew I was missing something...but I just don't see any options for interpolation or lack of in the scan manager...

It's a Visioneer 4400 USB scanner...

My neighbor is laffin his ass off and doesn't understand it either so I'm not alone.

Thanks

[edDV]

So your choices are 300dpi or 600 dpi for that object size.

BTW: "600 x 1200 dpi" is a marketing way of saying 600dpi.

[zoobie]

Allllllllllllllrighty then...600dpi it is.

Thanks

[ozymango]

Consumer models used to come in 300, 600 or 1200 optical resolutions. Some now go higher.

You can pick up a 2400dpi (optical) scanner for around a hundred bucks nowadays, and I love my (slightly older) Epson 3200 Photo scanner (3200dpi optical) that was a bit more but not obscene, about $300. And I'm sure it'd be maybe half that today, used.

If you're scanning any photos for possible use later on TV display, including HDTV, I highly recommend scanning them at the highest possible setting on your scanner (optical setting) and then edit later. You may discover that some images will look better if cropped even just a bit on your TV; I've found that out, anyway.

[edDV]

Consumer models used to come in 300, 600 or 1200 optical resolutions. Some now go higher.

You can pick up a 2400dpi (optical) scanner for around a hundred bucks nowadays, and I love my (slightly older) Epson 3200 Photo scanner (3200dpi optical) that was a bit more but not obscene, about $300. And I'm sure it'd be maybe half that today, used.

If you're scanning any photos for possible use later on TV display, including HDTV, I highly recommend scanning them at the highest possible setting on your scanner (optical setting) and then edit later. You may discover that some images will look better if cropped even just a bit on your TV; I've found that out, anyway.

I agree up to a point because these files get very large. At 600dpi for a 6"x4" object he is going to get a 24bit file of ~ 26MB. Higher bits per component takes that higher. Future consumer software will be oprating at 10 or more bits per component, so that needs to be factored as well. Smaller objects need more dpi, larger objects need less to get the same image resolution.

Storage is getting cheap but there is a time and volume element to this as well.

One needs to plan for the future uses of these stored files. A perfectionist is going to worry about not creating a master image that needs to be expanded or enlarged later.

There are two reasons to "go large". One is to allow cropping later with the resulting crop still having adequate resolution. The other reason is to allow extra resolution for image processing.

The film and video effects world think in terms of virtual rasters that are 2x, 4x, 8x, etc. larger than the "target raster" in this case HDTV 1920x1080. Effects motion filtering allows for trading image resolution for subpixel motion. This is how pro effects get super smooth XY motion and zooms where consumer applications snap to the next pixel with jarring results.

The eye tends to loose its ability to distinguish resolution as motion increases. MPeg takes advantage of this by reducing resolution in motion areas.

But the "Ken Burns" type slow pans and zooms over high resolution still images operates within the eye's full resolution response territory. This is where subpixel motion interpolation effects are really noticed. Burns did it all in high resolution film before transfer to to SDTV video. To get the same smooth motion in video without loosing resolution, you need to start with larger scans.

[ozymango]

I agree up to a point because these files get very large. At 600dpi for a 6"x4" object he is going to get a 24bit file of ~ 26MB. Higher bits per component takes that higher. Future consumer software will be oprating at 10 or more bits per component, so that needs to be factored as well. Smaller objects need more dpi, larger objects need less to get the same image resolution.

And this poor guy thought he was gonna get an easy answer! :P

Yeah, these files do get really large REALLY fast ... or not really that fast, actually, because if you scan a big image at 3200 dpi it takes bloody forever ... ...

This is one of those "it really depends on your needs and audience" situations, of course. Going off on tangents: I believe the orginal post talked about a post card, and when you scan postcards (or other similar graphics) they may not be actual photos, they may be dithered images where a de-screening filter on scan will give you the "best picture" depending on your playback options ... blah blah blah.

So, if you're scanning an image that you know will never been seen on anything but a TV, you might scan at one resolution. Or, if you also might print it later, that's a different resolution. Plus if this'll go on your webpage, there's another resolution ... sometimes one size fits all, sometimes it doesn't. Like we didn't already know that! :P

[junkmalle]

However if your originals are post cards, I'd say 600dpi already borders overkill, as the original print probably doesn't have that many dots per inch. Scanning photos would be whole other issue.

Raga is correct. Anything printed on paper proably was probably printed at 1200 dpi with 6x6 half tones. The final resoution is something like 200 dpi. Go much higher than that and you will just get big dots.

Here's a 1200 dpi scan of a postcard:



The same section at 300 dpi with descreening:

[edDV]

I agree up to a point because these files get very large. At 600dpi for a 6"x4" object he is going to get a 24bit file of ~ 26MB. Higher bits per component takes that higher. Future consumer software will be oprating at 10 or more bits per component, so that needs to be factored as well. Smaller objects need more dpi, larger objects need less to get the same image resolution.

And this poor guy thought he was gonna get an easy answer! :P

Yeah, these files do get really large REALLY fast ... or not really that fast, actually, because if you scan a big image at 3200 dpi it takes bloody forever ... ...

This is one of those "it really depends on your needs and audience" situations, of course. Going off on tangents: I believe the orginal post talked about a post card, and when you scan postcards (or other similar graphics) they may not be actual photos, they may be dithered images where a de-screening filter on scan will give you the "best picture" depending on your playback options ... blah blah blah.

So, if you're scanning an image that you know will never been seen on anything but a TV, you might scan at one resolution. Or, if you also might print it later, that's a different resolution. Plus if this'll go on your webpage, there's another resolution ... sometimes one size fits all, sometimes it doesn't. Like we didn't already know that! :P

True about the postcard but I was responding in the general sense as if it were a quality photograph. HDTV and "future" consumer printers are similar enough that the same scanning standards can be used. I think the "typical" HDTV 1080p 100 inch display is going to be the toughest target and this is looking out only 5-10 years.

My response was also offered for the person considering the future of consumer electronics not the current. The types of things Lucasfilm does now will be common in home video production when screens reach 100" 1080p. I am assuming when someone scans an object, they want that scan to be useful 5-10 years out. Many people even discard the original.

Added:

Everything above applies equally to digital photograqphy. When we buy that 8 Megapixel camera and look at the file with our computer and current printers, we find it hard to tell the difference between 3 Megapixel and 8 Megapixel. But if you display that file on a 100" 1080p screen from 3H distance, you will see a big difference.

[zoobie]

I've decided to just save them at around 25mb and burn them to a dvd archive.

Should be more than enuf as mentioned above.

[edDV]

I guess I should have changed the first post to say up to 2400dpi which I just used to scan a cropped postcard...It's almost 400mb.

I've decided to just save them at around 25mb and burn them to a dvd archive.

Should be more than enuf as mentioned above.

Anything over 600dpi on that scanner is interpolated and should not be used. Better to upscale it in a program like Photoshop if you ever have the need.

An analogy is the "digital zoom" on a still camera.

[junkmalle]

Some things I might point out for those who don't know:

The advertized scanner optical resolution doesn't mean that you will get full RGB resolution at that size. The sensors are usually laid out in something like: R G B G R G B G... A 600 DPI scanner has 600 of those individual sensors per inch. RGB pixels are then built by combining and filtering those R, G, and B sensors. That scanner might be able to resolve 600 black and white lines per inch when scanning in black and white (because you can use each of the primaries for black and white) but color resolution will be significantly lower -- closer to half the advertized resolution.

Along the other dimension the DPI really only refers to the stepping motor that moves the read head. The stepping motor usually takes steps much smaller than the optical sensors can resolve (ie, there's a large amount of overlap between samples along that dimension). So you don't really get the advertized resolution in that dimension either.

Fortunately, the average user has no need for more than 300 DPI of real resolution. As I mentioned earlier most images created via a printing press use large halftone blocks and have an effective resolution around 200 pixels per inch. Even color photo paper runs in that range. You really have to have black and white art prints to get higher resolution.

About the only things the average person might scan that can use more than 300 DPI is money (and your scanner will refuse to scan it!) and negatives or slides. But for negatives and slides you're much better off with a dedicated slide scanner.

[ozymango]

About the only things the average person might scan that can use more than 300 DPI is money (and your scanner will refuse to scan it!) and negatives or slides. But for negatives and slides you're much better off with a dedicated slide scanner.

I'll second everything you said except the very last line here -- yes, if you're working predominantly with slides and negatives it's certainly worthwhile to get a dedicated slide scanner, but you can get tremendous results with Epson's Perfection line with a flatbed scanner with slide/negative capability.

I know this from both experience (scanning several hundreds of slides, many quite old and in need of sometimes major color balancing and restoration) and from a couple of photographic restoration houses who've worked a lot with Epson's Perfection series of flatbed scanners that also handle negs and slides (with ICE technology that used to cost $$$). Yes, you can buy a much more expensive dedicated slide and negative scanner that will give you even better results, but the differences can be quite subtle. And value-wise, the Epson's are an extremely good deal.

[edDV]

At the other end of the spectrum you have museum quality scanners in various sizes. Creo makes a true 2540 dpi flatbed scanner (12"x17" bed).
Fuji makes a 5000 true dpi flatbed scanner with an even larger bed.

http://www.flatbed-scanner-review.org/Fuji_C550_flatbed_scanner/jd_Fuji_flatbed_scanner.html
http://www.flatbed-scanner-review.org/Scitex_flatbed_scanners_reviews/Scitex_flatbed_scanners.html

Back in the 90's Thomson had a project working with Paris museums to scan and document artworks. Part of the requirement was to produce a set of HDTV optical discs as a "low resolution" catalog. The plan included a slow 360 degree circular pan of 3D objects using some sort of imaging device. They were evaluating early HD television cameras but those just couldn't cut it.

[ozymango]

I've decided to just save them at around 25mb and burn them to a dvd archive.

Should be more than enuf as mentioned above.

Just to hit you with some more confusion from another direction, what format are you saving your images in? I highly recommend either TIFF if you don't have Photoshop, and PSD if you do have Photoshop -- these are both non-lossy formats so if you want to do any editing later, it's sorta like saving a video as an AVI file (non-compressed) and then converting to MPG-2 only at the end. I use Photoshop predominantly so I pretty much save PSD format (I like playing with layers when I'm fine-tuning contrast or trying to bring some details either forward or backward).

I guess BMP (Bitmap) is okay but I'm not crazy about it; JPEG is best used only for the end result (and if you have to work with a JPEG image, say from a camera that only saves as JPEG, save a master copy of the image as PSD or TIFF and do all your editing there, then resize and edit that image.)

Hope this isn't just throwing a bunch of buzz-words at ya. Let us know if you have more questions, we'll try to answer in English!