What is hi-res?

J
Posted By
JamesMGioia
Jul 16, 2004
Views
165
Replies
10
Status
Closed
Novice Question!

I am recieving photographed product images from my photographer.

He claims they are hi enough res for offset printing.

The files are coming to me as jpg’s. When I open w/Photoshop and look at the size of the file, the resolution is 72 dpi but the size is 30 inches by 30 inches. I really only need the files for print at 5 inches by 5 inches. If I resample the image in photoshop and set the res to 300 (which lowers the size to about 6 x 6. Does a true 300 dpi file result and will it work for print?

Any good info is greatly appreciated.

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P
PeterK.
Jul 16, 2004
Yes, the resolution is high enough if the 6×6 inch size is what you need. When you change the resolution with "resample image" unchecked, you’ll notice that the actual number of pixels in the image doesn’t change. The dialog box adjusts the dimensions of the image to show you how big the image can be at that resolution without interpolating. Now if you needed a 10×10 image at 300ppi, it wouldn’t be enough and you would have to judge whether or not resizing and interpolating would be acceptable, or get the image reshot with more pixel information (a digicam with a higher megapixel rating).
P
progress
Jul 16, 2004
ok…yes as a rule 300dpi AT THE YOUR PRINT SIZE is fine…its the common definition of high res if there is one.

dont resample the image…untick that box…you’ll then see that as you type in the 300dpi the size will fall from 30×30 to something like 7×7…so you have enough resolution to print at 300 dpi at the size you want. This is because the amount of pixels isnt changing, your just changing how many you pack into and inch, and because your not resampling the image size shrinks.

with resampling off…1000×1000 pixels = 10 inches x 10 inches @100dpi = 5 inches x 5 inches @ 200dpi

Try and get your head around resolution, its important. DPI (or to be pedantic PPI..pixels per inch) is a virtually dynamic measurement when dealing with images in PS…what you need to ensure is that you have enough pixels for the job without resampling. Resampling down is ok…resampling up is a bit of a dirty no-no, and only should be done when you are confident that the results will be satisfactory.

If you are uncertain as to whether you are resampling, then just watch the file size in MB…if your not it wont change, if you are then it will. If you intend to resample (to maybe reduce filesize) then as long as the file is at the size it needs to be and the dpi is right then your ok.

You may see people saying that 72dpi isnt any good for print, however if you turn resampling off, wind it up to 300dpi and your image is larger than you need then your still ok….if its not, your into that grey area which only experience will be able to guide you through.

Hope i havent confused you too much, but when you suss res, the it will be like someone has switched the light on.
KN
Ken_Nielsen
Jul 16, 2004
What is hi-res?

I’ve always wondered.
MO
Mike_Ornellas
Jul 16, 2004
It doesn’t exist anymore.
P
progress
Jul 16, 2004
yes its become a little like "give me an illustrator vector eps for your logo"…has become "wont a low res jpeg off the web embedded in an illustrator eps do?"
TL
Tim_Lookingbill
Jul 16, 2004
It usually depends on the output device. Send a 150 ppi file to some inkjets and you won’t see a difference if you had it at 300 ppi. But send the same 150 ppi file to a 2400 ppi/dpi? imagesetter and you’ll see a definite difference.
KN
Ken_Nielsen
Jul 16, 2004
Deep thoughts:

If you see pixels, but see them in high res, are they still pixels?
AS
Ann_Shelbourne
Jul 16, 2004
Depends on which end of the telescope that you are using.

Alternatively, is it the image or the viewer that is pixilated?
KN
Ken_Nielsen
Jul 16, 2004
The weekend awaits… Have a good one everybody,

Ken
AW
Allen_Wicks
Jul 17, 2004
Just to complicate, (at least) two other parameters are relevant to the real resolution/quality of the pix from your photog.

[A] The source of the file from photogs varies:

-In general if 35 mm film was properly scanned using a desktop scanner the functional resolution is what you see as described above when "resample" is left unchecked. E.g. in your specific example "about 6×6" is the size that would qualify as high rez for printing.

-In general if 35 mm film was properly scanned using a good drum scanner the functional resolution can be a bit higher. E.g. in your specific example "about 6×6" might be able to be "uprezzed" to a larger size like 8×8, evaluating individual uprezzed prints by trial and error.

-In general if a good pic was originally from an SLR digicam (no lossy film/lab/scanners in the workflow) you are likely to be able to uprez 100% or even more.

[B] The original quality of the actual photo (optics, lighting, exposure, tripod use, movement, etc.) over-rides everything. You cannot uprez – and may actually need to downrez – images that are not "very good" technical quality to start with.

Trial and error using your final output device is best, but not always practical.

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