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Size Question


HumblyLearning

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I just have a (hopefully) quick question. Let's say if I want to design a poster that, when printed, is 18" x 24", what size should I make it in Photoshop so when it prints, it is in the best quality?
 

ALB68

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I just have a (hopefully) quick question. Let's say if I want to design a poster that, when printed, is 18" x 24", what size should I make it in Photoshop so when it prints, it is in the best quality?
18 x 24 @ 300 ppi.
 

MrToM

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Let PS do it for you...

FILE > NEW

Set the 'Width' and 'Height' units to INCHES
Enter dimensions into the 'Width' and 'Height' boxes
Set the resolution to somewhere between 200-300dpi
Click 'OK'

You should now have a document at the right pixel dimensions.

Regards.
MrTom.
 

Hoogle

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Just get advise from your printers on what Bleed they require if any, I tend to always go a few mm larger than needed and never have any real detail towards edges it is usually something I do not care if it gets cropped off or not. I have had some bad experience with printers just going ahead and trying to resize it rather than just getting me to do it.
 

HumblyLearning

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Let PS do it for you...

FILE > NEW

Set the 'Width' and 'Height' units to INCHES
Enter dimensions into the 'Width' and 'Height' boxes
Set the resolution to somewhere between 200-300dpi
Click 'OK'

You should now have a document at the right pixel dimensions.

Regards.
MrTom.
Thanks everyone.

Where do I set the DPI? Here's what the screen looks like when I open a new document (see attached):
 

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MrToM

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Where it says 'Resolution'.

Change the units first to 'Pixels per Inch', then fill in the box.

Regards.
MrTom.
 

HumblyLearning

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I was taught that if I need to print one size, I need to make the poster a LOT bigger, like maybe triple the size of 18 x 24 or something. No? The resolution will do the trick?
 

MrToM

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...I was taught that if I need to print one size...
Sorry, I don't understand what you mean by this.

Any image can be printed at any size.
The PRINTED size (In mm, inches, miles, kilometers, whatever) is controlled by the RESOLUTION.

Resolution has 2 hats...
Hat #1:
The resolution of an image is no more than a label, a tag, a piece of information....written into the image file.
Your 'printer' (Of the Plastic kind) reads this piece of information and uses it to calculate how BIG your PRINTED image should be.

For eg.
An image 300x300 @ 300ppi would give you a PRINT size of 1" x 1".
An image 600x600 @ 300ppi would give you a PRINT size of 2" x 2".
An image 300x300 @ 150ppi would give you a PRINT size of 2" x 2".
An image 600x600 @ 150ppi would give you a PRINT size of 4" x 4".

Note: INCREASING the resolution DECREASES the PRINT size.
The 'Pixel Dimensions' remain CONSTANT regardless of the resolution used.

Hat #2:
The number of pixels in an image (Its pixel dimensions) can be changed.
This process is called 'scaling' or 're-sampling'.
The 'resolution' can be used to re-scale the image by adding OR removing pixels to or from the image.
This is not usually a good idea either way as adding or removing pixels is destructive and cannot be undone.

This can be used to keep the PRINT size CONSTANT by changing the number of pixels in the image.

For eg.
Take an image 300x300px @300ppi.
Its PRINT size would be = 1" x 1".
Keeping the PRINT size CONSTANT we could change the 'resolution' to say 150ppi.
The 'scaled' image would then be...
150x150 @150ppi = 1" x 1"

In other words the image has got smaller, its pixel dimensions are half that of before....which equates to a quarter of the total number of pixels....this is why it is not desirable to re-scale images.

Note: DECREASING the resolution DECREASES the pixel dimensions but keeps the PRINT size CONSTANT.

Keeping the resolution CONSTANT means:
1. You can re-scale the pixel dimensions by changing the PRINT size.
2. You can change the PRINT size by changing the pixel dimensions.

What you are doing at the moment is creating a NEW document that is already set correctly in terms of 'resolution' and 'pixel dimensions' to give you a PRINT size of 18" x 24".

If you change the resolution later WITHOUT re-scaling then you can have ANY size print you want.....thats Hat #1 BTW. :)

And yes, if you need your resolution to be 300ppi your settings are correct....they give you an image of 5400x7200px which is VERY big.....more than enough to work with.
(Its always best to have too many than too few)

Regards.
MrTom.
 
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HumblyLearning

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For example, if I want to print photos from my camera (like in the old days), I have to e-mail photos a LOT larger than just 4 x 6 (standard photo size) to the photo company. I would have to e-mail something like 800 x 600 pixels, just to get quality 4 x 6 photos. You see what I mean?

I honestly don't understand your last post.
 

MrToM

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For example, if I want to print photos from my camera (like in the old days)...
...OK....with you so far...
...I have to e-mail photos a LOT larger than just 4 x 6 (standard photo size) to the photo company...
...and thats where you lose me.

Why?
What do you mean by 'e-mail a LOT larger'?
How are you making these images 'larger'?

You then go on to say...
...I would have to e-mail something like 800 x 600 pixels, just to get quality 4 x 6 photos. You see what I mean?
No, not really.

You start by saying you have to 'e-mail' images bigger than 4x6.....this doesn't make sense....digital images have no linear size, only pixels.
You then go on to say that the image has to be 800x600....OK, thats more like it, that makes more sense, but why is 800x600 a 'LOT' bigger than what you had before?

What size was the image originally if 800x600 is a 'LOT' bigger?
800x600 is tiny by todays standards.

You see why it doesn't add up?

Lets take your 800x600 example though...
If you give that image a 'resolution' of 300ppi you would get a print 2.6" x 2".
To get a PRINT 4" x 6" you would first have to crop it to the right ratio.
800x600 is not the same ratio as 4x6.
The image would need to be 800x533px (taking the longest side as unchanged)

Then you would have to do one of two things...

1. Keep the resolution constant and INCREASE the number of pixels in the image.
2. Keep the number of pixels constant and DECREASE the resolution.

Option 1 would therefore need an image 1200x1800px.
Option 2 would therefore need a resolution of 133.3

Regards.
MrTom.
 
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ALB68

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For example, if I want to print photos from my camera (like in the old days), I have to e-mail photos a LOT larger than just 4 x 6 (standard photo size) to the photo company. I would have to e-mail something like 800 x 600 pixels, just to get quality 4 x 6 photos. You see what I mean?

I honestly don't understand your last post.
Let me try and help.
#1. Images to be printed need to be somewhere between 240-300 ppi. A desktop printer wants to see a minimum of 240 ppi. Commercial printers usually ask for 300 ppi. (I do 300 ppi as it works for both)All of this has to be based on pixel dimensions. For example, your poster is 18 " x 24" at 300 ppi. If you click the box for pixels per inch, you will see that your pixel dimensions are 18x300=5400 x 24x300=7200 (5400 x 7200) . If that same 18 x 24 was 72 ppi it would be 1296 x 1728. which is the same physical print size but the quality will be very poor because the PIXELS PER INCH is much lower and not enough information to return a good quality print.

#2. If you are putting work on the internet, ppi or resolution doesn't figure into this. The information is going to be displayed on a computer monitor and it only cares what the pixel dimensions are. The resolution can actually be 0 and your information will be displayed.

So, this simply boils down to you deciding prior to developing your work what the output is going to be, either on a printer or to the internet.
 
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ALB68

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Oprawindfury

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I just have a (hopefully) quick question. Let's say if I want to design a poster that, when printed, is 18" x 24", what size should I make it in Photoshop so when it prints, it is in the best quality?
From my experience I always try to keep it to the actual print size and the right resolution. Of course doing a big banner is different =)
 

Tom Mann

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@Oprawindfury -

There are two major reasons I don't recommend CMYK to visitors to this forum. The first is that most visitors to PSG have very limited experience with Photoshop. Many (most?) don't even know how to use the basic tools yet, let alone be familiar something as advanced as color management, color profiles, and certainly not the intricacies of commercial printing. IMHO, recommending "CMYK" is not a good idea.

For example, which variant of CMYK should they use (see attached screenshot)? What about dot gain, total ink limit, type of separation, black generation curve, and the other parameters that are needed to get reasonable looking output from a particular press. Of course, newbies won't have a clue about any of this, so, of course, you have to tell them to contact the printer and ask for the ICC profile that that particular press uses. Then, if it's a big operation with multiple presses, each with its own slightly different ICC profile, there's a good chance the printer will simply say, "send it to us in sRGB or Adobe RGB, and we'll do the optimal conversion".

The second major reason I don't recommend CMYK to visitors to this forum is that most of them are talking about very small numbers of prints (...maybe just one) that they will have done by an on-line printing service (eg, Mpix, etc.), or by the local Office Supply store or some local mom-and-pop parcel store. 99.9% of these operations use inkjets, color lasers, dye subs, or something similar, but never an offset press, because all their business is short runs. The printer driver software for each of these types of printers is highly specific to that particular model, mfgr, etc. It expects RGB input and does an optimized conversion to the inkset recommended for that printer. These days, this is often many more than the 4 basic CMYK inks. In the best of circumstances, if you send the printer driver some ICC version of a CMYK file, the driver software will be smart enough to first do a reasonable conversion to (say) Adobe RGB, and then do the conversion to the (say) C1C2M1M2Y1Y2K1K2K3 flows that this particular model of inkjet needs to produce good output. So, again, by suggesting CMYK, at best, you've wasted their time, and most likely, you've actually reduced the quality of the output they will receive.

Exactly as Larry, ALB68, pointed out, these days, the best recommendation (at least to most visitors to this forum) is for them to work in sRGB, a least-common-denominator color space and let the printer do the conversion for them.

Tom M

PS - For those users who actually need to use CMYK, I just found a nice, fairly simple article about how to prepare such files. Check it out - it's a nice read:
http://www.damiensymonds.com.au/art_newsprint.html
 

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Tom Mann

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...Of course doing a big banner is different =)
At the risk of stating the obvious, the OP of this thread is only talking about an 18 x 24 inch print. This is hardly a "big banner" or poster -- it's more like a decent sized photographic print, LOL.

Tom M
 

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