Best DPI for printing to A4 (1 Viewer)

Mark,



Yes it does, because of PSD, which would warn me immediately.

For example you give me such a file 800x800p @ 72dpi, say 1.5Mb original, you add 40 layers to that file which gives me a file size of 60Mbs.

You instruct me that Birdwatching magazine want to use this photo on their cover would I look at it.

1) The alarm bells are ringing because it is a PSD. Not only on the format but the first thing a postscript RIP does is flatten this file, which could cause conflict, so I have no idea how this image will print.

2) It has forced me to open that file and check it.

3) I flatten, correct to the right resolution and then phone you to say that it will print at the size of my thumbnail.

Now that is an extreme example. Now you send me the same tif file at 12Mbs with the same instructions, I don’t need to open it, because I’m back on the phone to you saying this will not enlarge to A4, give me a suitable image


This is why I disagree with all those digital books because they spout off the digital formulas, of how to do this, that and so forth. I look at their book and think well why didn’t you follow what you preached in the previous chapter; perhaps then your images will not look like they were shot at 6 minutes past midnight. Again extreme but you can’t generalise over printing techniques because there are a million of different printing media out in the world, all different.


On digital enlargement this is limited by resolution to suit the printing process.

With film you have no restrictions only on the scanner and film quality.


PS: Frank, I do like your Moon shot.

pe'rigin said:

Mark,



Yes it does, because of PSD, which would warn me immediately.

For example you give me such a file 800x800p @ 72dpi, say 1.5Mb original, you add 40 layers to that file which gives me a file size of 60Mbs.

You instruct me that Birdwatching magazine want to use this photo on their cover would I look at it.

1) The alarm bells are ringing because it is a PSD. Not only on the format but the first thing a postscript RIP does is flatten this file, which could cause conflict, so I have no idea how this image will print.

2) It has forced me to open that file and check it.

3) I flatten, correct to the right resolution and then phone you to say that it will print at the size of my thumbnail.

Now that is an extreme example. Now you send me the same tif file at 12Mbs with the same instructions, I don’t need to open it, because I’m back on the phone to you saying this will not enlarge to A4, give me a suitable image

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pe'rigrin, I am not having a go or saying what you do is wrong for how YOU work with YOUR images...but it will not translate to others without explination.

Also, to be a pedant about file format - if I send you a 48mb TIFF file for an A4 or letter sized cover, how do you know what resolution the file is without opening...it could have 100 layers in it...TIFF is not a 'flat' format, which is why I used it for my example above.

pe'rigin said:

This is why I disagree with all those digital books because they spout off the digital formulas, of how to do this, that and so forth. I look at their book and think well why didn’t you follow what you preached in the previous chapter; perhaps then your images will not look like they were shot at 6 minutes past midnight. Again extreme but you can’t generalise over printing techniques because there are a million of different printing media out in the world, all different.

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Which book(s) are you talking about? That might help me understand your point. Assuming you are talking about typical digital photography books, just because the publisher uses a poor reproduction technique does not mean the author's advice on printing to inkjet printers is incorrect...

pe'rigin said:

On digital enlargement this is limited by resolution to suit the printing process.

With film you have no restrictions only on the scanner and film quality.

Click to expand...

Why? How can there be no restrictions to resolution with film?

pe'rigin said:

Depending on your printer (the better the printer the higher image file size you'll need), on average if you can get a file size of about 5-10Mbs, you'll get a good inkjet print @ A4...

Now you send me the same tif file at 12Mbs with the same instructions, I don’t need to open it, because I’m back on the phone to you saying this will not enlarge to A4, give me a suitable image

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Pe'rigin, both of the above quotes are from you (in different posts).

And you are saying that a 5MB file will print well at A4 and a 12MB file will not!! (I assume that when you use the abbreviation Mbs you intend it to mean megabyte and not megabit.second).

mike from ebbw said:

Thanks for all your time and input guys but I am completely lost now!I tried upsizing and printing one of my gallery images to A4 and it was rubbish(unsurprisingly).

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Upsizing is rarely a good thing. The image editor has to add pixels to the image. These pixels are obviously totally the invention of the editor. It follows a certain logical algorithm (probably duplicates existing pixels, etc), but it is still manufacturing pixels out of thin air. So, you will get lousy results usually.

Bottom line - save your originals. Also, don't ever downsize with resample for printing. Adjust the dpi without resample instead - the image size in pixels will remain the same, but it will print larger or smaller depending on the dpi you chose. In fact, except for web display, emailing, or desktop wallpaper, you practically never downsize.

PS: Frank, I do like your Moon shot.[/QUOTE]

Pe'rigin - technically, you are (IMO) as incorrect about the "Moon shot" as you are about your theory on print resolution.

Firstly, the moon shot is more correctly a sun-shot, being a total eclipse of the sun. Whilst this naturally requires the presence of the moon, the emphasis changes.
I agree though (being an amateur astronomer as well as a birder) that it is a fine image of the eclipse - prominences showing well!

FRANK - what gear did you use to capture this?

Regarding print resolution, I have to agree with the others who say print resolution is all about pixels and nothing to do with file-size.
Also disagree with your comments on conventional film. Unless I missed your point, this has obvious limitations in the grain which in a way is the equivalent of digital pixels.

To the original poster - I've had reasonable success with increasing image size in PS. Although this won't add information to the image, it will reduce the blockiness by adding extra pixels. I don't care what anyone says on the theory of this - it works!

Good thread this!

Must remember that "adding pixels" is a fact of life in digital photography : it happens in Bayer demosaicing (in the vast majority of digital cameras and RAW converters) and often in printing whether by editor or printer driver. Don't know if we've lost you Mike, but these two essays by Mike Chaney (author of highly regarded Qimage software) might be useful intro reading :
http://www.steves-digicams.com/techcorner/January_2005.html
http://www.steves-digicams.com/techcorner/january_2006.html
Glad you don't seem too distraught

Astrokev said:

To the original poster - I've had reasonable success with increasing image size in PS. Although this won't add information to the image, it will reduce the blockiness by adding extra pixels. I don't care what anyone says on the theory of this - it works!

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I agree that upsizing will of course reduce the "blockiness" - more pixels getting printed at a given size will print smaller - i.e. less blocky.

I guess I'm mostly trying to steer people away from routinely using resize/resample to deliver the image they want for printing. From stuff I've read before on this and other forums, I sometimes get the impression that people routinely use upsizing as though it is part of a normal workflow, without any regard to what it does to an image. I think it should be a LAST RESORT.

Astrokev said:

I agree though (being an amateur astronomer as well as a birder) that it is a fine image of the eclipse - prominences showing well!

FRANK - what gear did you use to capture this?

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Thanks for the kind comments. It was shot in Turkey during last March's total eclipse. I used a Canon 20D with a 100-400mm lens. Problem with pictures is that they just can't capture anything like the real thing. So I didn't really get enthused by them. My friend Didi has done a much better job that I (especially with the processing of them).See her pics here

I was trying to think of an image I had that had a very small amount of fine detail to show how that can greatly influence file size.

Ok, let’s have one final go at this.

Technically, I’m correct Frank’s shot is of the moon, surrounded by the sun’s flair, semantics I know.

My theories on resolution, well I must have got it all wrong for the past 20 years advising the World’s largest corporations how to go digital.

The digital books are generally most of them. If you are going to regard yourself as a professional then that advice you give must be precise.

Let’s take this example on a fictitious book, ‘Let’s get down and dirty with digital’, by Fred Bloggs produced in the UK

I buy the book here in the UK; I lend it to you Mark, in the states.

Let’s take the pinnacle point of an iceberg as the analogy for this discussion for one process only, litho printing. Forget all the other factors, which influence how you correct your image.

The pinnacle point being that the USA has a different colour and printing system to us in the UK. How can Mr Bloggs advise you Mark? How to prepare your images for reproduction.

Now, if Mr Bloggs printed a disclaimer, which stated this: -

“ The above details should be regarded as guideline only, we strongly recommend that if you are sending your images to a third party for reproduction, you obtain from them the correct colour profile to suit their production requirements’

Now, it’s a long time since I’ve read any of these books, if they have since printed similar in the text, then disregard my rantings.

Now, if we go back to Mike’s original questions “How to print to A4”.

I’m no clairvoyant, I don’t know Mike’s image sizes, printer, paper, ink or what resolution he needs to print at.

Roy came up with the best answer, stick at this and see.

RAH came up with the technical answer, but, it’s missing one vital bit of information, what is the PRINTING RESOLUTION required by Mike’s printer.

Me, well, I know that somewhere between 5-10Mbs is the correct resolution Mike needs. The worst he could do is over compensate and have too much information, all that will happen is it takes his computer a bit longer to print. But, what is important he is not loosing image quality.

The professional way to do this was to ask Mike to send me his printer requirements, and I would send him back the colour profile. But, he doesn’t want to get embroiled in pages of technical nonsense, life’s too short.


Re: layered tif.files I cheat, I have software, which tells me everything about any file.

pe'rigin said:

RAH came up with the technical answer, but, it’s missing one vital bit of information, what is the PRINTING RESOLUTION required by Mike’s printer.

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I guess I just assumed he has a modern inkjet printer that can print photo quality prints. With most printer drivers these days, you pick the paper you are using, and then just pick the quality - i.e. with my Epson 1280, "Speed" or "Quality." It's kind of like falling off a log - i.e. you don't really have to know the technical things like the dpi of the printer (and in fact, with my Epson, it is decidedly hard to actually find it out).

In other words, seems to me if you use high-quality paper and a high-quality driver setting, and you stick to an image dpi of not less than say 180, you'll get good results.

I'm not saying, by the way, that getting the print to match the screen (color, brightness, etc) is easy - as we know, this can be tough.