Preparing images to print

[WJT]

I am getting ready to sell a few images but am new to this digital business and struggling to maintain the file size when exporting from my Aperture oftware. I have been exporting in Jpeg and my file are too small. Is Tif better, and does the MB mean anything or is it just the DPI I have to consider? Thanks in advance.

[bambleweeney]

Jpegs should be ok to print (or so I'm told), I use printing software to print Photoshop .psds personally. When you say file size do you mean the size of the file on the disk or the pixel dimensions ? A shot from a 10 or 12 megapixel camera will print quite happily at A3 or even A2. Essentially it's pixels that make the difference, a 200 pixel square image is never going to look great printed at A3, a 4000 pixel square image is going to be pretty good.

[Polar01]

Wayne: your printer does not care what format your files are in, jpegs, psd's, tiff's, dng's etc., etc., etc.,. If you are printing large prints 44" x 66" than a format that preserves all the data is best to save the image in. If you are only going to print everything at 8 x 10 or smaller than a jpeg is fine. Remember that a jpeg is a file that is the lowest possible standard if you were to think of it in the building code, psd's and other are above code. I would strongly suggest that you read some of the forms on file formats and printing, get a good handle on what you want to do, as you seem to be a little lost. Then come back after you have a stronger understanding and idea of what it is you want to do and need to ask. There are a lot of questions that need to be answered before I or anyone can really help you, ex: why are you exporting your files as jpegs?, it it becasue your camera does not shoot in raw?, if it does, are you shooting in raw?, if not why?, etc,..

Allan

[WJT]

Thanks Allen,

I'm shooting in RAW at about 25MB, and importing into Aperture. I seem to be loosing so much MB and PPI when I process the picture. Then when I am exporting I'm loosing more again. I thought that the image wouldn't print in RAW so had to be converted to JPEG or TIF?

[Polar01]

The image as far as I know will not print from raw, coluld be wrong, once you have processed image I would save as either a PSD or a tif as every thing is there, and if need be you could return to rework the image. Last image I printed yesterday was a print 12" x 36", 6.24GB at image size, when saved reduced size to 6" x 18" was 1.56GB that is 24 times larger at printing than your 25MB, it was saved and sent to the printer as a psd file. So save as either a psd or a tif. Some people will work on an image as a tif than save as a psd or the reverse that way they know that the one format is work in progross and the other format is a finish image. Hope that is of some use others are way more informed on this than me.

Allan

[Polar01]

Just thought of something, when in ACR what are the settings at the bottom of the image, click on that, make sure DPI is set to a mim of 240 best 300 or 360 depending on your printer. space is set to what your camera is in sRGB or adobe RGB 1998, depth is set to 16 bits/channel, and the size is at 25.1+ this should give you the biggest file size.

Allan

[Colin Southern]

Hi Wayne,

Ignore PPI -- it's only used in conjunction with the specified image size to calculate the number of pixels to be retained, whereas in reality, you want to retain all pixels. So in reality you don't need a target PPI; number of pixels available divided by the size of the image will none-the-less produce a certain PPI, but at the end of the day, "it is what it is" ... there's no need to change it.

JPEG file size does give a hint as to the amount of information in a file (like I'd be kinda worried if I was printing one of my landscapes at 22 x 44" (normal size for me) and the file size was only 25kb, but assuming you still have full resolution - and the jpeg quality hasn't been set to a low value - then you should be fine. JPEG is optimised for small file size; it's absolutely fine for display and printing ... just not good for heavy editing.

Happy to check over one of your images for you if you'd like to send me one, if this helps.

[Colin Southern]

Just thought of something, when in ACR what are the settings at the bottom of the image, click on that, make sure DPI is set to a mim of 240 best 300 or 360 depending on your printer. space is set to what your camera is in sRGB or adobe RGB 1998, depth is set to 16 bits/channel, and the size is at 25.1+ this should give you the biggest file size.

Allan

Hi Allan,

Um, not quite ...

Changing the PPI setting doesn't affect the file size in any way, shape, or form - it's simply divided into the number of pixels in the image to give the image a set "dimension" (which in itself is irrelivant for everything except how big fonts of a certain point size appear on the image relative to everything else).

DON'T set the size to anything with a + after it - it upsamples the image which will make all operations slower and can also degrade image quality. If one REALLY needs to up-sample an image then it can be done afterwards, but there's usually no point as images for online display are always severaly down-sampled, and images for print are upsampled by the printer driver automatically anyway (where the "whatever" PPI of the image is turned into the actual DPI of the printer).

sRGB -v- Adobe RGB doesn't need to be set to whatever the camera is set to; assuming a RAW print, the file doesn't have a colourspace assigned to it until it's spat out of the RAW converter (regardless of what the camera is set to).

[Graystar]

You need to tell us how you're printing the images. Are you printing them yourself? Using a printing service? Who is that service? And what size are you printing at? Also, what camera are you using?

This is a large subject with a bit of confusing terminology. It's hard to cut to the chase with such questions because there are so many factors.

You're not losing megabytes or PPI when you process the image. Images are stored using different methods which result in different storage sizes. JPEG image compression is one of the most efficient, and the resulting files are much smaller than other methods. At the time you save the image you must select a quality level. If you select the highest quality, then the JPEG copy will be practically indistinguishable from the original.

The PPI value that is stored with the image can be ignored. Its original purpose is to record the scanning resolution of a document so that scanned documents could later be reproduced in their original size. Digital images don't use this value. Cameras and software will insert a range of different values from 72 to 300. The printing function of software will use this value if you select "original size" when you print. Normally, images are printed "size to fit" as well as "borderless" to fill the paper. So images don't have an "original" size...the "size" of an image is whatever paper you decide to print on.

[WJT]

Thanks all for your explanations. I'm shooting with a Canon EOS 5D MII, and wanting to print at 400mm by 600mm. I am talking to several printers but don't have enough knowledge to have a decent conversation. I've now read the tutorials which help and I can see that my camera creates good size pixels. I have also established that somehow I am not exporting my images at 300 ppi, even though I thought I had set the default to that (only 72 ppi). This must be the main problem. One more question; What is the difference between Megabytes and Megapixels? This is another point of confusion for me. Thanks in advance.

[Colin Southern]

Thanks all for your explanations. I'm shooting with a Canon EOS 5D MII, and wanting to print at 400mm by 600mm.

Hi Wayne,

Max print size for a given resolution is one of the most commonly misunderstood things in printing. Basically - because viewing distance increases with print size (with the exception of photographers where it's limited only by the length of their noses), the question isn't really "how big can I print for a given number of pixels" - it's "what is the minimum viewing distance for a given number of pixels at a given size". Often you'll hear figures like 300DPI being the minimum print resolution -- and if that's for a photo in a glossy magazine then it may well be useful (although still overkill in my opinion) - but if it's a 20 foot wide billboard that's going to be viewed from 50 feet away then even 10DPI would look sharp.

In reality, folks worry about these things far far far far too much - a minimally cropped 400 x 600mm print from a 5D2 will look just fine (I've got 1.06m x 500mm prints shot with an 8MP 20D hanging on my gallery wall next to same size prints shot with a 21MP 1Ds3 -- and you really can't see any difference at normal viewing distances (and minimal difference at "up close" distances.

Correct sharpening makes a FAR bigger difference than the native resolution (or even the lens used).

[WJT]

Thanks Colin, One of the printers said the same but the other is determined that it should be 300 DPI. I supposed these pictures will be viewed at about 6 feet plus. I am just being a bit cautious as I don't want to get off on the wrong foot when I start to sell prints. I've worked out that although I set my defaults to export at 300PPI, it needed to be done every time, so I should be right now. Just one more question though; is 16 bits going to give me a better result than 8 bits?

Wayne

[Colin Southern]

Hi Wayne,

Thanks Colin, One of the printers said the same but the other is determined that it should be 300 DPI.

Unfortunately, it's a common knee-jerk reaction from those who don't understand. I've had these in the past were calender photos were rejected because they weren't 300PPI - we just up-sampled them which does exactly NOTHING - handed them back - and they were much happier with them.

I supposed these pictures will be viewed at about 6 feet plus.

At 6 feet plus even 100PPI would probably be OK.

I am just being a bit cautious as I don't want to get off on the wrong foot when I start to sell prints. I've worked out that although I set my defaults to export at 300PPI, it needed to be done every time, so I should be right now.

It doesn't quite work that way; you only have so much information to print so basically, the more you "squish it together" (eg higher print density) then the smaller the print. If you have a file that's 3000 pixels wide by 2000 pixels high - and you export and then print at 300PPI - then it'll be 10 inches wide by 6.67 inches high. If you export and then print the same file at 100 PPI then it'll be 30 inches wide x 20 inches high. You could up-sample the image to 9000 pixels x 6000 pixels and print it 30 x 20" @ 300 PPI, but (this is the important bit) DOING THAT DOESN'T ADD ANY INFORMATION TO THE FILE. If the information wasn't captured by the camera then it can't be added by software later.

Just one more question though; is 16 bits going to give me a better result than 8 bits?

In terms of printing - in the real world - no. In terms of having the file in 16 bit whilst it's being processed in the likes of Photoshop, the answer is "yes, it CAN make a difference, but it depends on what you're doing to it". If you're doing big adjustments then 16 bit is always safer.

[Photon Hacker]

Thanks all for your explanations. I'm shooting with a Canon EOS 5D MII, and wanting to print at 400mm by 600mm. I am talking to several printers but don't have enough knowledge to have a decent conversation. I've now read the tutorials which help and I can see that my camera creates good size pixels. I have also established that somehow I am not exporting my images at 300 ppi, even though I thought I had set the default to that (only 72 ppi). This must be the main problem. One more question; What is the difference between Megabytes and Megapixels? This is another point of confusion for me. Thanks in advance.

The printing pixel (Measured here in PPI, pixels per inch) setting stored in the file don't makes a difference in image encoding for any algorithm I know of. Setting it higher will not make a higher quality print, it will just alter the default printing size for the image (Unless the printing software ignores it anyway), but usually we have a size in mind when printing than we use, so the printing pixel density stored in the file is irrelevant.

As for the difference of megabytes and megapixels, it's very much like a kid asking the difference between "72" and "57" in the sense it seems straightforward to answer but it's not because the question reflects a lack of understanding of the underlying concept than the straightforward answer wouldn't address. A satisfactory answer would rather address the underlying concept making the original question no longer relevant.

WJT: Do you understand the meaning of the quantities you're querying about and its effects?. I suppose you don't because otherwise you wouldn't need to ask these questions. I strongly suggest you investigate further these topics. Look up pixel, byte, pixel density, color depth in your favorite source of information. Wikipedia was linked here, those articles cover the issue much better than we would be able to do in a reasonably sized forum post.

Good luck !.

[WJT]

Thanks Mario, thanks Colin. Its is hard to even ask the right questions when your at such a level. I will endeavour to study up. Any links would be appreciated. Regardless I have learnt a lot to date through this site. :-)

[Colin Southern]

Thanks Mario, thanks Colin. Its is hard to even ask the right questions when your at such a level. I will endeavour to study up. Any links would be appreciated. Regardless I have learnt a lot to date through this site. :-)

Hi Wayne,

In summary, only down-sample your images for online display -- if you're printing, just keep them at full resolution.