300 dpi question - Page 6

**Marc Sabatella** · 10-28-2009, 01:43 PM

Originally Posted by K-9

As far as why I save as a TIFF. I do this mostly with photos that I need to touch up. For instance to remove a cigarette butt from the ground in a photo. AFAIK, you can't do stuff like this in Lightroom, and you can't do that with RAW files in Photoshop.

Sure you can - just not with ACR. Take your RAW file - as first processed by LR - directly into Photoshop, do your cloning, and *then* save as JPEG or TIFF or whatever you like.

If you want to print 4x6" at 300dpi, you need 1200x1800 pixels (since 4x300 - 1200, and 6x300 - 1800) or more. If you've got that many pixels, I *promise* you'll get 300dpi if you print 4x6". It won't matter what EXIF says, and I swear there is nothing more to it that: dpi is *literally* dots per inch. If you have 3104 dots (as you normally do, in the short dimension, from a 14MP camera), and you print those 3104 dots at 4 inches wide, that comes out to 3104/4 = 776 dots per inch. Period, end of story. Meaning iIf you have 3104 dots, you have *more* than enough resolution for 4x6 prints at 300dpi - you have enough for 4x6 prints at 776dpi. Most printers won't actually do an better than 300dpi, so some of those dots will be thrown away by the printer - but that is its business, not yours.

Alfisti · 10-28-2009, 07:08 PM

Originally Posted by K-9

Maybe I'll get it one day.

As far as why I save as a TIFF. I do this mostly with photos that I need to touch up. For instance to remove a cigarette butt from the ground in a photo. AFAIK, you can't do stuff like this in Lightroom, and you can't do that with RAW files in Photoshop. So, I take the TIFF, use the clone stamp and do whatever other airbrushing, stamping out I have to do in PS CS2, then save it as a JPG when I am done. I was under the impression you lose less quality when doing this to a TIFF than with a JPG.

Yeah that makes sense, but you can open as a tiff directly from LR into PS.

Ben_Edict · 10-29-2009, 04:26 AM

Originally Posted by K-9

Maybe I'll get it one day.

As far as why I save as a TIFF. I do this mostly with photos that I need to touch up. For instance to remove a cigarette butt from the ground in a photo. AFAIK, you can't do stuff like this in Lightroom, and you can't do that with RAW files in Photoshop. So, I take the TIFF, use the clone stamp and do whatever other airbrushing, stamping out I have to do in PS CS2, then save it as a JPG when I am done. I was under the impression you lose less quality when doing this to a TIFF than with a JPG.

Alright, this is a new question, which has nothing to do with the resolution (dpi) discussion in this thread, but I give you a short answer:
Basically you are very right to make any edits in TIFF-format, especially as you can open and save an edited file as often as you want, without quality loss.
JPGs is a very convenient file format to send images for printing or whatever. But as any time you save an JPG again, some details get lost and artefacts may be added to the image, you will quickly see a deteriotation of the image, after a couple of edits. How much quality is lost, depends for example on the quality setting you choose during resaving.

The best strategy is, to keep the edited versions in TIFF or PSD format (both can be compressed without loss) on your machine or on DVD to enable a later additional post-processing run. Then you can generate new JPGs whenever you need one.

Another point worth noting about JPGs and TIFFs is, that JPGs don't include transparencies, which is a nuisance, if you include images in Layouts or you need them for screen design. Also, TIFF is the format of choice, if you need files in 4C (4 colours, Cyan, Magenta, Yellow, Black) for print publishing. And lastly TIFFs can also accomodate basically any colour space (ProPhoto, AdobeRGB etc.), whereas JPGs are supposed to be sRGB (and if you add for example ProPhoto to your JPG, you'll get an unpleasant surprise during the printing stage...)

Ben

HGMonaro · 10-29-2009, 07:27 PM

The problem K-9 is facing is users/customers that don't know much about what they're asking for either.

They would accept a file with 3000x4000 pixels and a EXIF tag of 300dpi
but may not accept a 3000x4000 pixel file with an EXIF tag of 72dpi.

Marc is correctly stating that this file will print exactly the same, Graphicsgr8s is correctly saying that PS will look at the two files slightly differently in that it will think there canvas sizes are different. InDesign might place the image on a layout in different sizes initially, but once you've resized to suit your document, they are for all purposes, fundamently the same (assuming 'resize' means shrink which it generally will)

If the customer knows what they are about, they'll look at the available pixels and maybe the file size (to check that it hasn't been compressed to much) and slot it into whatever publication they are creating.

This reminds me of times when I hear someone quote I need "20MB" files... that is probably determining that a low resolution highly compressed image isn't acceptable purely as a by-product of the fact that generally to create a "20MB" file it's going to need some decent resolution at a decent size although if using JPGs that isn't always the case. With any compressed format, the actual scene influences the final size.

Just cause I've got nothing to do... couple of quick examples...

Files size using a 5000x4000pixel image of pure white
PSD - 970KB
Files size using a 5000x4000pixel image of pure black
PSD - 970KB
Files size using a 5000x4000pixel image of busy scene
PSD - 49,769KB

Using the Black Only file and saving as a TIFF
TIFF no compression - 58,604KB
TIFF with LZW compression - 815KB
BMP - 58,594KB

Using the Black Only file and saving as a JPG
JPG Quality 0 - 115KB
JPG Quality 50 - 115KB
JPG Quality 75 - 230KB
JPG Quality 100 - 230KB
(quality 51 was 230KB as well so it must have overheads that determine the filesize when using this example... so not a very good example!!!)

so...

Using the "Busy Scene" file and saving as
TIFF no compression - 58,623KB
TIFF with LZW compression - 20,952KB
BMP - 58,594KB
JPG Qual 100 - 7,837KB
JPG Qual 75 - 3,205KB
JPG Qual 50 - 1,425KB
JPG Qual 0 - 454KB

So in this case, I could send them the "20MB" TIFF but the 'Qual 100' JPG wouldn't be any good to them, even though a print from either would be indistinguishable. Interestingly, when displayed full screen, it's very hard to see the differences between these compressed JPGs, zoom in and the differences are very apparent although the "0" qual one is surprisingly 'good' considering!

Alfisti · 10-29-2009, 07:56 PM

Exactly. BTW any piccies of the HG?

*Eaglerapids* · 10-29-2009, 08:17 PM

Originally Posted by K-9

As far as why I save as a TIFF. I do this mostly with photos that I need to touch up

I'm sorry K-9, I misunderstood. I thought you meant you saved all your pefs as tiffs. If I need to take a photo into Photoshop for whatever reason I work on it as a tiff also and of course save the edited tiff copy in case I want to work on it later.

*graphicgr8s* · 10-29-2009, 09:21 PM

Something else to think about if you're going to print on an offset press. Offset is a cmyk process. When they are placed into a layout program and eventually printed it will be darker. Second to last step is to convert to CMYK then sharpen. Then save it as a tiff.

HGMonaro · 10-29-2009, 10:19 PM

my HG Monaro! (yes some silly bugger put a Ford like shaker on it at some stage... I haven't got around to getting rid of it... only owned the car for 16 years!!!)

Originally Posted by graphicgr8s

Something else to think about if you're going to print on an offset press. Offset is a cmyk process. Jpegs are RGB can't save a jpeg as cmyk. When they are placed into a layout program and eventually printed it will be darker. Second to last step is to convert to CMYK then sharpen. Then save it as a tiff.

Currently doing something along these lines and the printshop has asked for me to convert pictures to CMYK before loading them into InDesign and producing a PDF... I've been doing this to the various JPGs I've been supplied (resaving as JPG) and the PDF produced looks fine however I haven't got a sample back from them (was hoping to get it today). The JPG saves as CMYK and when reopened, says it's CMYK, is it really CMYK?

*graphicgr8s* · 10-29-2009, 10:32 PM

Originally Posted by HGMonaro

my HG Monaro! (yes some silly bugger put a Ford like shaker on it at some stage... I haven't got around to getting rid of it... only owned the car for 16 years!!!)

Currently doing something along these lines and the printshop has asked for me to convert pictures to CMYK before loading them into InDesign and producing a PDF... I've been doing this to the various JPGs I've been supplied (resaving as JPG) and the PDF produced looks fine however I haven't got a sample back from them (was hoping to get it today). The JPG saves as CMYK and when reopened, says it's CMYK, is it really CMYK?

My error. I had something turned off for a job I was doing at home. It's cmyk. Hey, I am human after all.

HGMonaro · 10-29-2009, 11:12 PM

Originally Posted by graphicgr8s

It's cmyk.

ok, maybe my proof won't be all black