Scanners, resizing, attachments etc

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tom hardwick
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Joined: Apr 8 1999

Great news that this topic has its own heading. Now hopefully we can learn the magic of Photoshop; figure out what resolution we should be flatbed scanning at; learn more about level tweaks and unsharp masking; discover the wonders of cloning and layering and talk mega pixel CCDs till we're blue in the face.

I shall be visiting here often. But while I'm here, why is it that they sell photo glossy paper that wrinkles after my Stylus Photo has sprayed it with ink? OK I should go for 200gm paper, but in that case what's the thin stuff produced for?

tom.

seaDog
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Joined: Sep 3 2000

Just a quick one, I saw you were using an Epson Inkjet, this will happily produce 10x8 at 200dpi so you need to scan in the range 250-300dpi, anymore and its a waste if you are just printing unless you are doing something specific of course. Theres one of your questions answered.

regards

Alan Roberts at work
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Joined: May 6 1999

I use an Epson Stylus 750, and while the gloos paper does wrinkle immediately after printing (that's while the ink is still damp), it dries out flat after a day or so. It hasn't been a problem to me.

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peter millard
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Joined: Oct 19 2000

There are lots of different papers out there for lots of different uses. The "Photo Glossy" is really a thin proofing paper, but it's very neutral; the "Photo Paper" is like a heavyweight bromide paper, but has a warmer base colour, the "Heavyweight Matt" can be a nice paper if you want a dead matt surface, but it does take longer to dry (especially important if you're going to laminate it) and the blacks can lack a bit of depth, whereas the "Premium Glossy" is a bright high gloss paper with a similar feel to glossy resin-coated papers with deep rich blacks - but I've found it to be a generally a touch cyan.

I use the thin stuff to proof out pictures when the client isn't expecting them to look like photographs, ie to provide a neutral representation of what I'm supplying on disc, and the regular Photo Paper for just about everything else, unless the prints are going to be handled a lot. If you think your printer is over-inking the paper, then try selecting "glossy film" as the paper type in the Epson driver, which reduces the ink flow to prevent puddling on non-absorbent media.

As far as resolution goes, I've always had the best results when the image res. is directly divisible into the printer res. Example, if you're printing at 720dpi on your Epson, then you'll get the best results with the image at either 360 dpi or 180dpi. After some exhaustive testing on lots of different images, I now only ever use 180dpi files to print from - the difference them and 360dpi simply isn't worth bothering with - try it and see for yourself!

Hope this helps.

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Peter Millard
petermillard.com

Peter Millard
www.petermillard.com

Alan Roberts at work
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Joined: May 6 1999

Excellent advice, Peter. I also try to stick to simple ratios, it gives the interpolator less ways of getting it wrong.

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peter millard
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Joined: Oct 19 2000

Absolutely, Alan, although there's no actual interpolation taking place here; if your output device is running at 720dpi, but printing an image at a quarter of that resolution (180dpi), then it's effectively making 4 printed dots for every single image pixel.

This wouldn't be the case if you were printing a 300dpi file on a 720dpi device - you end up with "2 and a bit" printed dots for each pixel, which is where you start to get jagged lines and moire patterns.

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Peter Millard
petermillard.com

Peter Millard
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Alan Roberts at work
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Joined: May 6 1999

Yup, that's what I meant by interpolation. The "enlargement" of a pixel in whole numbers is a special case in which all the coefficients in the interpolator are 1 or zero. In other cases, you're at the mercy of the interpolator designer, he may have just copied the nearest pixel (crudest possible scenario) or done a really fancy 2d interpolation using many adjacent pixels to calculate the required value. It looks better but it costs more and takes longer.

Either way, there's an interpolator involved. The same argument holds in resizing images in Photo Shop or Paint Shop Pro etc. The bigger the interpolator aperture, the higher the resultant quality, and Photo Shop is currently at the top of my preference list for just that reason (it's interpolator is equivalent to a 4x4 aperture whereas Paint Shops's is nearer 3x3, Photo Shop removes more high frequncies while Paint Shop leaves more alias components).

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tom hardwick
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Joined: Apr 8 1999

fascinating to read all your replies, guys. I'm glad Bob started this up - I can see I'm going to learn a lot here.

tom.

peter millard
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Joined: Oct 19 2000

Fair point, though I think we may be splitting hairs here, Alan; I wouldn't refer to a 180 pixel/inch image coming off a 720 dpi printer as being interpolated, as the pixels are not being "enlarged" - on the contrary, they're already 4 times the size of the dots the printer produces. I'm sure you're right that the term interpolation refers to any adjustment of the image either way, but I think it's more commonly used when you're enlarging an image and some clever software has to fill in the gaps between the original pixels by clever guesswork (as in most programs), or by borrowing bits of data from the adjacent pixels (as in the Fuji Super CCD.)

I agree that Photoshop's Bicubic interpolation is very good indeed, although there are better applications available - at a price! Leaf Colorshop (sic) is excellent, but only works with 16 bpc HDR files, and only in CMYK - and you have to use a Leaf or Sinar digital back to get it (I got the software with mine, but not the dongle that let's you use it - a snip at around £1500...), or there's a more up to date version called Resolute, also by Leaf systems, which will work on any digital file but comes in at just over £2000 - as if the £12-16K you spent on the back wasn't enough!

Photoshop's looking better all the time, don't you think?

All best.

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Peter Millard
petermillard.com

Peter Millard
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peter millard
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Joined: Oct 19 2000

Yep, I'm glab Bob started this as well - at last I can feel as if I'm contributing something (all that talk about codecs and frame rates was making my head burst...)

Resolution, colour depth, dots per inch - that's just simple maths, isn't it? Much better!

Good weekend, all.

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Peter Millard
petermillard.com

Peter Millard
www.petermillard.com

Alan Roberts at work
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Joined: May 6 1999

Peter, yes, good stuff costs lots. And I regard extrapolation and interpolation as mathematically identical, they are both filters, it's just that one invents data while the other throws it away. The analysis is always the same.

As far as the maths is concerned, I'm happy to have feet in both camps, stills and video. The numbers aren't hard but you need to know what you can ignore in most cases. Come to think of it, isn't that the definition of an engineer?*

* "An engineer is someone who can do for a pound what anyone can do for £10", don't ask me who said it first, but it certainly feels true.

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red
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Joined: Oct 1 2000

Peter,
If you are scanning at 180 to print at 720dpi what would you scan at to print out at 1440dpi?(epson 740).
Cheers,Red

peter millard
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Joined: Oct 19 2000

Still 180dpi, as it's directly divisible into the print resolution of 1440dpi, though on some subjects you may get a better result from a file at 360dpi.

Personally, I rarely print at 1440dpi - takes too long and the results aren't worth the extra time or ink, unless you've a particular problem (usually banding in a background or sky, or some other niggle.)

That said, it's really horses for courses - run a couple of tests and see which works best for you, on any particular photo.

Hope this helps.

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Peter Millard
petermillard.com

Peter Millard
www.petermillard.com

red
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Joined: Oct 1 2000

You know I had a feeling you'd say that,yet on my set up(Astra 1220s,Epson 740)there is a marked difference between 720 and 1440.By that I mean the 1440 print really gets near to looking like a photograph but the 720 looks what it is,a print.Are there any printer or scanner tweaks I'm missing? Red.

Stephen Carter
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Joined: Nov 18 1999

This has all got very complicated. Its reasonably simple really as long as you realise the following:
There's scanner DPI and Photoshop dpi which are the same thing. Then there's Epson Printer dpi which is another matter. When Epson talk about 720/1440 dpi it is something to do with the fact they are printing in lots of colours. The actual dpi as we know it is a lot less. The best inkjet printers work at around 300 dpi whatever they claim to do.
Fact: You need the Epson set to 1440 dpi to get it to work at 'near photo performance'
Fact: If you feed it with images greater than 300 dpi from Photoshop it can't tell the difference and you only slow things down a lot.
In practise 300 dpi is great, 250 dpi is OK,
200 and less is getting a bit dodgy.
When you scan you should always set the scan dpi to end up with 300 dpi when you print - so if you scan a 100mm x 150mm print at 600 dpi then it should be OK to print out up to 200 x 300. (A4 Near as..).

Stephen Carter
www.seraphmedia.org.uk

peter millard
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Joined: Oct 19 2000

To be honest, I don't do a lot of scanning, so apologies if the following comments are pretty general. Are you working from tranny or print originals? I know that flatbed scanners aren't at their best when scanning trannies or negs, especially smaller formats, as they rarely have the optical resolution to do them justice. Be wary of using interpolated resolutions provided by the scanner, especially on small-format originals; you're more likely to get a better result from scanning at the highest optical resolution, and enlarging the file in Photoshop, though obviously a lot will depend on the optical resolution of the scanner and how far you blow up the image..

If you're scanning a print, then scan at a higher resolution than you need, and reduce the file to your print resolution in Photoshop (or whatever). Scan at the highest bit-depth your scanner allows, as this defines the "pool" of colour data from which your final 24-bit image is created. Don't try printing an image that's greater than 24-bit, as it will almost certainly be out of the gamut of the printer.

Make sure you're printer head alignment is OK, and that the nozzles are all clear - click on the little "tools" button in the Epson driver to run the tests. Try printing a file that you didn't originate (a download, say, or one pulled off a cover-mounted CD) at both 720 and 1440dpi - if there's still a marked difference between them, then your printer may need some attention; if not, then your scans/scanner may need some help.

Make sure you're printing an RGB image. All Epson Printers are RGB devices (despite the fact that they use CMYK inks, these are not the same CMYK that printers use for producing 4-colour litho print, eg. Computer Video magazine) - if you send an Epson printer CMYK data, its "colour management" will convert it to RGB before printing, using who-knows-what settings.

Are you using decent paper (eg.Epson Photo paper, or Premium Glossy) and inks (ie. Epson, not 3rd-party*)? The inks are particularly important, as the viscosity is essential to keep the nozzles clear - and the nozzles/print head are permanent features on Epson printers, not replaced with each ink cartridge; replacing the print head in an Epson is not generally economical. * I mean cheapo compatible cartridges, btw, not those from specialist ink & media suppliers like Lyson.

Again, sorry if the above is too general or if I'm stating the obvious, but the difference between printing at 720dpi and 1440 shouldn't be that great, as long as the original is in good shape.

Let us know how you get on.

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Peter Millard
petermillard.com

Peter Millard
www.petermillard.com

peter millard
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Joined: Oct 19 2000

In reply to Stephen Carter:-

Stephen, I agree that this has become fairly complex (and it certainly isn't helping Tom Hardwick get anywhere with his choice of paper) but I do feel you're muddying the water a little by presenting opinions as facts. I mean no offence, and I certainly don't want to get into a "duel" or a pi**ing contest, but your statement that "...the best inkjet printers work at around 300dpi..." is just plain wrong. On the contrary, Epson printers in general (and it does vary with the specific model) use many different coloured dots of ink for each of the 720 or 1440 dots they lay down per inch - indeed, far more than can be distinguished by the naked eye. Some large-format inkjet printers (used for printing large point of sale ads, banners, short-run posters and the like) have a relatively low dpi count compared to desktop models, but they usually get around this by making multiple passes, which effectively doubles (or more) the output resolution. You also view these larger prints from a greater distance, which doesn't hurt either!

You said:
Fact: You need the Epson set to 1440 dpi to get it to work at 'near photo performance'
I disagree. Certainly, on some subjects, in certain conditions, printing at 1440dpi is desirable, but only rarely have I found it to be necessary. That's just my opinion, but it is borne out of having made photographic prints on my Epson printer virtually every working day for the last 2 years, and most days in the preceding 3 years - I'd be happy to send you some samples if you're interested; 'mail me your address off-list if you like.

You also said:
Fact: If you feed it with images greater than 300 dpi from Photoshop it can't tell the difference...In practise 300 dpi is great, 250 dpi is OK,200 and less is getting a bit dodgy.
Again, sorry, but I disagree. As I said earlier up this thread, I've had the best results from my Epson when the image res. divides neatly into the printer res. because then each "dot" of image is printed by 2 or 4 (or 8, whatever..) dots from the printer. My experience is that a/ an image at 300dpi will actually print better (on a 720dpi Epson) if it's res'd up in Photoshop to 360dpi, and b/ that it won't suffer at all by being reduced to 180dpi. Again, I'm happy to send some samples - or you could easily try it for yourself.

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Peter Millard
petermillard.com

Peter Millard
www.petermillard.com

red
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Joined: Oct 1 2000

I'm just going to analyse that little lot,
(where's me calculator). Thanks for the tips guys, much appreciated.I'm sure this forum is going to pay dividends for people like me who are just getting their toes wet.
For Tom,they sell the thin stuff because they can flog it cheap and move it by the shedload.It's g.s.m (grammes per sq mtr) relates directly to it's thickness and we all know what happens when you put water on tissue paper. I've worked in the paper industry for 20 yrs and modern manufacturing standards are allowing the production of thinner and cheaper papers(a lot of it recycled)but it doesn't mean to say it's any good.Basically you get what you pay for.The lowest g.s.m I've used so far is 194 and there's been no wrinkles whatsoever even at 1440 dpi because the moisture content of the ink is not enough to warp that thickness of paper.

Stephen Carter
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Joined: Nov 18 1999

I certainly bow to your greater experience on this and apologise for expressing opinions as facts. I am however convinced I am not that far wrong. I think what I was trying to say was that when Epson print out their 1440 dots or whatever they are printing several printed dots to represent each scanned dot if you see what I mean(ie one for each of RGBY). i.e. if you managed to scan at 1440 dpi on your scanner your printer would not be able to use all the info. I am under the impression that it produces 4 dots of ink for every electronic dot offered to it so to speak. So with an incoming dpi of 360dpi it gives its maximum printed dpi of 1440
If you set the printer to 720 dpi on the printer control panel you are printing to an equivilent scanned resolution of 180dpi which I would accept is probably OK on a lot of photos but not others.
I would be quite happy to be enlightened on this if it is bunkum.

[This message has been edited by Stephen Carter (edited 24 October 2000).]

Stephen Carter
www.seraphmedia.org.uk

Ronnie
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Joined: Nov 28 1999

An interesting site to visit on this subject is:
http://www.scantips.com

kosh
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Joined: Oct 30 2000

Tom...
I haven't read all of the above, there's so many so sorry if i repeat!!....
i'm a pro photographer and have worked for Jessops as their Digital specialist...
RULE No1: NEVER scan higher than 300dpi 1:1 or lower than 180.
RULE No2: IGNORE what ur printer outputs at!!(always print in highest print quality poss for photographs & turn on microweave, on an epson photo) it's mumbo jumbo about scan at this if ur printer's that!! scan at 300 @ 1:1 and output a 1440 with high speed off as well)
RULE No3: ALWAYS run unsharp mask on a scanned image (between 70 & 100%)
RULE No4: PLAY it safe if you've got an EPSON printer Use their INK and paper (They really do know what their doing!! i've tried HUNDREDS of combinations and their's best!)****BUT do try Jessops Glossy FILM and double sided stuff (both are FANTASTIC!!)***(contradiction I know,, but exceptions!)
RULE No5: ALWAYS go DOWN never UP!! don't interpolate if you can help it BUT if u can't then use PHOTOSHOP 'Bi-cubic interpolation' you CANT beat it!!!
OK i've said my bit...hope it helps. anything else....just Holla

PS Don't buy any Epson Premium Glossat the MO if ur buying it for light fastness.... someone's boobed and heads are gonna roll soon!!!!

[This message has been edited by kosh (edited 30 October 2000).]

[This message has been edited by kosh (edited 30 October 2000).]

peter millard
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Joined: Oct 19 2000

Hi Steven.

Yup, if I was misreading your original post my sincere apologies.

I think what I've been trying to say is that, rather than be a slave to the "always scan at..X and always print at ..Y" school of thought, don't be afraid to just try it out. The beauty of working digitally is that you can have a go at all these different conmbinations of scan and print resolutions quickly, easily and cheaply, and work out which one works best for you on any given image.

And whatever you do, don't let the technology get in the way of the pictures!

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Peter Millard
petermillard.com

Peter Millard
www.petermillard.com

NNSW
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Joined: Oct 8 2000

To Kosh

You recommend never to scan at more than 300 dpi.Is this for flat bed scanners? But what about film scanners (i.e for transparencies and negatives)?

NNSW
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Joined: Oct 8 2000

To Kosh

You recommend never to scan at more than 300 dpi.Is this for flat bed scanners? But what about film scanners (i.e for transparencies and negatives)?

Alan Roberts at work
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Joined: May 6 1999

I'm 100% with Peter. Don't let the technology stop you experimenting. It's only by trying things out for yourself that you'll ever be able to come back here and tell us we're wrong. I've been messing around with video and stills and such for more years than I care to contemplate, and still manage to be surprised by discoveries with alarming frequency.

Go to it. Try it for yourself and let us know what happens.

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Stephen Carter
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Joined: Nov 18 1999

300 (or thereabouts) dpi is rule of thumb for flat bed 1 to 1. You need to multiply accordingly if you are enlarging or zooming in. If you are film scanning you need to divide the final print size by the transparency size and multiply 300 by that amount to give the scan dpi. Usually you end up running film scanners at max dpi if you are printing.

[This message has been edited by Stephen Carter (edited 30 October 2000).]

Stephen Carter
www.seraphmedia.org.uk

kosh
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Joined: Oct 30 2000

NNSW:
Exactly the same 300 dpi 1 to 1.
REMEMBER this does not mean... slap a neg in and scan the hole neg @ 300dpi only.
ITS ur OUTPUT size that counts 1:1 so that may mean scanning the 135mm neg at 2700dpi to get something like 12 x 8 print @300dpi (thats a guess calculation by ther way!!) most software will let u choose the output size and resolution and it will work out the SCAN resolution needed.