Sizing an image for printing

[Bluie]

Hello


I am to get a one-off photo printed commercially to fit a 20" x 30" frame, so if I allow for a 1" white border all round - between the photo paper and the frame - that would mean a total image size of 18" x 28".


From what I have read, print resolution should be about 350 px/inch. Yet, if I open up my image in Photoshop, then go to Image | Image Size, type in 350 px/inch
for Resolution and 28" (width) x 18" (height) under 'Document Size' (please see attachment), even at 33% zoom, the image won't fit on my screen!


Is there something I am not doing correctly?


Thanks.

 

[MrToM]

Not really no.....you've done everything right although I would argue if its the 'best' way to do things.

From your screen shot it looks as if you 're-sampled' the image......the checkbox at the bottom is checked.....was this intentional?

You can get away with a resolution of 200ppi, and certainly no more than 300ppi, but it does depend on what the print is for and if it needs to be really good or just OK.

You are on the right track when it comes to sizing.....its just simple maths......x pixels @ xppi = linear dimension.....pretty simple.
What you need to remember is that with any equation like this changing one element means changing one or both of the others to compensate.

What were the original pixel dimensions to begin with? re-sampling should really be avoided for a good print but if your original image doesn't have enough pixels to print at even say, 200ppi then you'll have to resample....unless you have a larger image?

Give us the image info before you tried this and we can through your options.

Regards.
MrTom.

PS...also, why if you ADD an inch to the frame does the image get smaller? 20x30 to 18x28 ????
Shouldn't that be 22" x 32" ?

 

[Bluie]

Hello Mr Tom


Thanks again for your reply.


No, the resampling was already checked and I have just left it the way it was.


Oh, OK, so I can have a resolution of 300.


The quality doesn't have to be spectacular but acceptable. It's for a poster to go in someone's dining-room, the only print in the room so it will stand out.


The original resolution was 72 px/inch and measures 19" x 11".

Thanks again.

 

[MrToM]

No worries...

I need to confirm something as you may have missed my question...

I asked for the pixel dimensions but you gave me the resolution and print size.....using the simple maths I outlined before I calculate the pixel dimensions of your original image to be:

72 x 19 = 1368px WIDE.
72 x 11 = 792 HIGH.

So 1368px x 792px.
Is that correct?

Use the Info Bar (Set to 'Document Dimensions') or the INFO PANEL to confirm the pixel dimensions if you need to.



Having the Pixel dimensions on display is far more useful than how big the file-size is.....I don't know why Adobe don't have this as default but then I could say that about a lot of things...LOL.

Anyway, just confirm those Pixel Dimensions for me and we can go from there.

Regards.
MrTom.

 

[Tom Mann]

Two thoughts:

1) If Mr.Tom's calculation of pixel dimensions of the original image is correct (ie, 1368px x 792px). That's way too small to make a print of that size and have good quality. Even with the best resizing software, the image will look soft and funky if printed that large. Hopefully your starting image is not the one we have been discussing, and has much larger pixel dimensions, but we simply are unaware of this. For a print that large, I like the starting image (ie, before any resizing) to be at least 3 kpx in the shorter dimension.

2) When you say that you are sending your image out to be printed "commercially", most of the time, people mean sending it to some place like Shutterfly, Walmart, Vistaprint, Mpix, etc., and not to some printing service that only deals with pro photographers & graphic artists. The reason I make this distinction is because the first type of printing service will utterly and completely ignore any ppi specification and/or information on dimensions (in inches/cm) that you have laboriously put into your file. FWIW, the majority of the images they print have no such information included because that's what comes out of most cameras, LOL.

All this type of printer will care about is that your image has enough pixels in each direction, and that the aspect ratio of the image file is reasonably close to the aspect ratio of the print size you have selected (so that they don't have to crop too much away or leave white space). They will do all the resizing for you, so, like Mr. Tom said, un-check the "resample" option box.

Tom M

 

[Bluie]

It says:

Document Size:

Width: 11.111 inches
Height: 14.264 inches

Resolution: 72

Pixel Dimensions:

Width: 800
Height: 1027

I am referring here to the original image.

The image I am working on now, which I have changed the resolution of to 300, has this:

Document Size:

Width: 28 inches
Height: 17.997 inches

Pixel Dimensions:

Width: 8400 px
Height: 5399 px

Those document size measurements are to cater for a 20"x30" frame with a 1" border all round.

Thanks again.

 

[Bluie]

Hello Tom Mann

I presume Mr Tom is a different person!

OK, I will uncheck resampling - I probably need to read up on that.

Yes, it's a shop in the UK call Max Spielman - a photo retail chain. They have said bring the image in to the shop on a Flash drive.

Thanks for your post.

Steve

 

[MrToM]

...I presume MrTom is a different person!...

...and don't you forget it!


Right then...here's the situation regards the info you provided...

As Mr Mann has pre-emptied, the image size just isn't big enough to print an image @300ppi.

The maths clearly show this...
Width 800px and height 1027px:
800px @300ppi = 2.6" (800 / 300 = 2.6)
1027px @300ppi = 3.4" (1027 / 300 = 3.4)

This gives a PRINT size of 2.6" x 3.4"
This, is no-where near your desired size of 20" x 30" (I assume thats the PRINT size you want? You didn't answer that question either...??)

Even @200ppi you still only get:
800 @200ppi = 4"
1027 @200ppi = 5.13"

NOTE: The lower the ppi the bigger the image!

So what to do?

You essentially have three choices:
1. Go down the pub and think about it for a few pints...[recommended]
2. Re-sample the image...[NOT recommended]
3. Do the whole image again with enough pixels to give you the PRINT size you want... [Also recommended but probably not practical?]

This means #2 is probably the choice you'd go for....re-sample the image.

This is not ideal but unless you can do #3 its about the only option you have.

Right....re-sampling...
You've already done this albeit inadvertently, but lets do the maths to see what we need for a 20" x 30" PRINT size.

Assume a resolution of 200ppi as the absolute minimum we can get away with...ie, the print will still look reasonable....ish.

20" @ 200ppi = 4000px
30" @ 200ppi = 6000px
Ratio = 4:6 or 2:3 or 1:1.5

Unfortunately, 800 x 1027 is a ratio of 1:1.28, so there needs to be some cropping done first....regardless.

Its always best to crop BEFORE re-sampling as the process works better with pixel dimensions that are divisible by 8.
You'll have to decide how to do this depending on what you want to lose (crop) from the image, but you need to have an image that has a RATIO of 2:3.

For example....as it stands you could crop to 684 x 1026px ....thats at a 2:3 ratio AND divisible by 8.

Once cropped you can then re-sample it as you did before....set the resolution to 200ppi and type in 20" for the width.....with 'constrain proportions' on, the height should change to 30".

That will give you want......whether that gives you a good enough print or not I couldn't say, but without re-doing the whole image again this is your only option.

Theoretically, ANY image can be printed at ANY size just by changing the resolution....but the outcome may not be acceptable.

Regards.
MrTom.

 

[Tom Mann]

Yup, we are definitely different people, LOL!

May I ask how your starting image got so small? 800x1000 pixels is only 0.8 megapixel. That's tiny. These days, even the least expensive point and shoot cameras are at least 10 megapixels. If it's a digital photo, someone must have either cropped it, or intentionally down-rez'ed it (eg, to send it in an email or to post online). Are u sure that there isn't a larger version of that image around somewhere, e.g. still in the camera?

BTW, the "after" size is essentially meaningless when it comes to estimating how blurry the final print will be. This is because there is no new info in the "after" version. 90+ percent of the pixels in it are just "best guesses" that the software made up just to keep things smooth looking, not jagged / pixelated.

Tom M

 

[ALB68]

Bottom line..what you have won't work. My guess is that it was a download from the internet, judging from the original pixel dimensions you stated. Start over with something large enough and with adequate resolution.

 

[Bluie]

I feel like going to the pub after that lesson in Archimedes!

I think what you are saying is that the original is too small?

OK, this is what I have - more or less following you:

240 resolution, 18" high by 28" wide, 'Constraint Proportions' ticked, 'Resampling' ticked.





On screen it looks OK.

I don't know. I thought Mr Tom, and Tom, might be Photoshop brothers - if not akin?!

Thanks for all your help - both of you.

Steve

 

[MrToM]

...I feel like going to the pub after that lesson in Archimedes!...

Option 1 it is then!

Honestly, this is no more difficult than AxB=C.

The problem is, as you say, the limited pixels to work with.

With no larger image to use you have to use what you do have to give you the best output possible.....which may or may not be pleasing to the eye.

From a distance it'll look great though!

If it doesn't look too good then maybe make the print size smaller.....that'll make it look better closer up....depends how close you want to stand to it I guess.

Anyway, read through what I suggested slowly and you'll see just how simple it is........especially after a pint or four when you have the advantage of reading it twice at the same time!

Regards.
MrTom.

 

[ALB68]

I feel like going to the pub after that lesson in Archimedes!

I think what you are saying is that the original is too small?

OK, this is what I have - more or less following you:

240 resolution, 18" high by 28" wide, 'Constraint Proportions' ticked, 'Resampling' ticked.

View attachment 54065



On screen it looks OK.

I don't know. I thought Mr Tom, and Tom, might be Photoshop brothers - if not akin?!

Thanks for all your help - both of you.

Steve

What you see on the screen basically has nothing to do with how it will print from a quality standpoint. Understand that a computer screen cares nothing whatsoever about anything except the number of pixels. Resolution means nothing to it. You can prove this by setting the resolution to 1, and it will look the same on the screen. The printer is a totally different output device and it has to have enough "resolution" or density of pixels in order to print and give you acceptable output. I would think if the poster is going on someone's wall it's going to be inspected pretty close, if it were mine I would aim for 300ppi.
If you start out with something that is 72ppi (which is pretty much what internet documents are published at) and you need 300ppi and a size like your trying to print, there is really not a very good way to get there from here. You can re-sample all you want to, put the printed quality is still going to suck. Good luck!

 

[Bluie]

I will experiment at 260 and 280 resolution but as you say it means nothing on a PC screen. In reality, nobody is going to go nose-to-nose with a print in a frame in someone's living room and, if they did, I am sure they could pick out mistakes. It's more of a general impression which that print conveys.

I am grateful to you all for spending so much time on this.

Now, where was that cider...................?

 

[ALB68]

I will experiment at 260 and 280 resolution but as you say it means nothing on a PC screen. In reality, nobody is going to go nose-to-nose with a print in a frame in someone's living room and, if they did, I am sure they could pick out mistakes. It's more of a general impression which that print conveys.

I am grateful to you all for spending so much time on this.

Now, where was that cider...................?

If it was more critical, or you come out with something that is really bad, you could possibly do this. I did this this week as a matter of fact and it worked like a charm. I needed to have some photos of some people from an old school yearbook, small photos. I put my digital camera on a copy stand and photographed the images at a high quality setting. Take the 72ppi digital image and change the resolution without resampling. The size would be whatever Mr Tom stated above.Then print the small print on your desktop printer on some good quality photo paper. Then either photograph it or scan it on a digital scanner. Now you would have something you could work with to accomplish goal size. Again, good luck.

 

[Tom Mann]

Bluie: "I will experiment at 260 and 280 resolution..."

I'm sorry, but please don't spend too much of your time on such experiments. Unfortunately, tweaking the PPI value won't make any improvement whether you look at the result on a screen, or whether you have your photo store print it out to a size that you specify in your order.

Part of the reason for the confusion that's rampant in this area is the the word, "resolution" has two different, but somewhat related meanings, and it's easy to confuse the two. For example, in most of the post in this thread, the word "resolution" has been used as Adobe's synonym for PPI (pixels per inch). This is technically correct.

However, PPI is certainly not the concept that most people are thinking of when they say something like, "The resolution of that picture is high (or low)."

What people usually mean is that in a high resolution photo you can see the leaves on the trees over on the next hill, whereas in a low resolution image of the same scene (ie, same magnification, same light, same croping, etc.) you can't make out individual leaves, but only the branches on those trees, and this remains true whether you make a billboard sized print out of it and then re-photograph the billboard with a microscope -- you just aren't going to be able to resolve individual leaves if the initial resolution of the image is too low.

What we have been telling you is that the resolution (common usage of the term) of your starting image is too low. It's pixel dimensions are simply too low to resolve a lot of different small objects in the image, so if you blow it up, no matter what PPI setting you use, you still won't resolve any finer detail.

HTH,

Tom M