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Old 08-07-2007, 11:17 AM   #1
Ashlie
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Default High Res Images for Pre-Press Printing

I have several images at 72 dpi but the actual size of the photo is huge - 36 inches by 20 inches. The photos will not appear larger than 4 x 6 in print. I have been told by a professional photographer that 72 dpi should be fine for print if the image is very large and it's printing at a smaller size. However, the printer disagrees even after printing several of my 72 dpi images in brochures without any problems. He says I must convert my 72 dpi files to 300 dpi which just makes the file size huge! So I am in the middle of the professional photographer and the "professional" printer/graphic designer. Does anyone know if the photographer is correct? So far in my experience, as long as the image itself is large, 72 dpi is ok for print. I am thinking that maybe the printer isn't as knowledgeable as he tries to appear but I really don't know...any advice or input?
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Old 08-07-2007, 11:50 AM   #2
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I am not an expert on this, but I do understand that the term “dpi” is not really useful here.

What you care about is the pixel count. If you open one of these huge 72 dpi images in Photoshop and use Image > Image Size, you will see the pixel dimensions at the top of the panel.

If you unclick the Resample Image button at the bottom of the panel and then use the Document Size controls to change the width of the image to the width you need (or change the height; either one will work) you will see the other dimension and the resolution change to reflect the new values.

If the resolution is in the appropriate range for the size you have chosen, you have enough pixels to print. Of course, if the image needs cropping, sharpening, color or tone control adjustments, probably best to do those first.

Save the result of all this as a new image for this particular job. Leave your original data intact, in case you need to use the image again in some other way.

It is always preferable to prepare images for a project to suit the layout — do not leave resizing, etc., for the printer to do.

   
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Old 08-07-2007, 12:17 PM   #3
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ashlie: Does anyone know if the photographer is correct? So far in my experience, as long as the image itself is large, 72 dpi is ok for print. I am thinking that maybe the printer isn't as knowledgeable as he tries to appear but I really don't know...any advice or input?
Actually, on level they are both correct but the printer is not interested in doing what he considers your work for you...sooo...at Kathleen suggested, you need to go in and resize the image...

Personally, I would not UNcheck "Resample Image" option for two reasons:

1. You are reducing the image size so you will not lose any pixels by having resamping checkmarked

2. There is more flexibility in leaving resampling checkmarked


Here is what I would probably do:

1. Open the file in Photoshop

2. Image > Image Size

3. With resampling checkmarked: enter 300 in the Resolution area (since that is what your printer wants)

4. Enter "4" in either the "Height" box or the "Width" box (basically, enter "4" in whichever field has the smaller value. The other field will be automatically filled in with the appropriate value to maintain the image proportions--see note below

5. Click on the "OK" button

6. File > Save As to a new file name--don't overwrite your original file!!!

Note: if in step 4, entering a "4" does not give you a "6" in the other field, then you will need to play with the sizing. What I often find works is to make the image a little bit bigger and then crop or select the image size I want:

1. Use the Crop tool--fill in the "width", "height" and "resolution" (use 300 there) at the top of the screen to 4x6 or 6x4--as appropriate


2. Or use the Rectangular Marquee tool--change the "style" field at the top of the screen to "Fixed" and then enter the width and height as appropriate--then ctrl-c to copy the selection and then New > File and paste...

Hope that helps...let us know if not...

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Old 08-07-2007, 12:51 PM   #4
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Quote:
Originally Posted by terrie View Post
Personally, I would not UNcheck "Resample Image" option
That’s interesting. Someone taught me to uncheck it, and it does give me more information (or at least it seems that way).

I will try it both ways next time I do it.

As for cropping, I tend to crop visually — to make the image suit the text or the layout (or just my eye) — not by the numbers.

Some things I don’t (or can’t) crop at all, of course.

But if you are working with casual images (snapshots, say) you often need to crop — to make head shots all about the same size and to align the eyes for a row of them, for example; to crop out the lady in the polka-dotted dress whom the editor hates; that sort of thing. And sometimes you crop to zoom in on some feature of an image, to make an inset of a map, for example.

All by eye.

   
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Old 08-07-2007, 12:59 PM   #5
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To add to what the others have said, a photographer who specialises in photography for offset printing once told me that when resizing images, you can get away with a final file size increase or decrease of up to 30% but no further.

So note the size of the file before you start the resizimg as Kathleen and Terrie have suggested, and check the final file size after the resizing.

FWIW, I tend to use Terrie's method of resizing.

   
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Old 08-07-2007, 01:37 PM   #6
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Thanks for the input. I am not leaving any resizing for the printer to do. I just want him to print my files as is. I create flyers and brochures and so the photos do not appear large on the page. I usually give them PDFs so I don't understand what his problem is. He has already printed tons of my files with this same 72 dpi issue and I didn't resize the photos at all. All the files are printing fine. Then the last job he had problems and said that the 72 dpi was the problem which didn't make sense to me becasue the photo was sharp but faded. Then I changed it to 300 dpi and he still had the same problem. Turns out it was because the photo was in RGB instead of CMYK. He still said the problem was the resolution but I think he is wrong. Why would 8-10 other files print perfect with 72 dpi image while this one file allegedly didn't. All settings were the same on all photos. It's the same person who loves to take those large format 72 dpi pictures and doesn't want to change because the photog told him not to... Personally, I'd prefer 300 at least accross the board but I have to work with what people give me. I may not have been clear before - I am not asking the printer to print straight photos so he doesn't have to resize any images. I am asking him to print flyers with photos in the layout.
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Old 08-07-2007, 01:43 PM   #7
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The printer is not doing any work for me. I have already layed out the entire file and all he has to do is print. I am not printing straight photos that he has to resize; I am printing brochures and flyers which are already completed by me before the printer gets them. All I really want to know is: Are 72 dpi images ok to use for print as long as the actual image size behind the scenes is quite a bit larger than it will appear in the layout?
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Old 08-07-2007, 02:04 PM   #8
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When you turn resampling OFF, changing the DPI changes the size in inches, both of which are convenient lies that we, the image and the software participate in.

ImagePixels / DPI = Inches
ImagePixels / Inches = DPI

With resampling OFF, you can change the DPI or Inches to anything you like; the image itself will not change one whit, except for the 8 or so bytes that store the little white lie (aka Inches and DPI).

If you turn resampling ON, then the image does change along with the white lies.

   
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Old 08-07-2007, 02:22 PM   #9
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Quote:
kt: That’s interesting. Someone taught me to uncheck it, and it does give me more information (or at least it seems that way).
One thing that I tend to do is to uncheck "resample image", change the ppi/dpi to what I need and see if the resulting height/width is larger than I need. If it is, then I check "resample image" because it's more flexible and resizing smaller is not going to require interpolation--resizing larger is where things can get ugly...'-}}

Since the printer said 300ppi/dpi, I figured that checking "resample image" was going to give Ashlie the option to set the res at 300 and then she can fiddle with the size as necessary...


>>As for cropping, I tend to crop visually — to make the image suit the text or the layout (or just my eye) — not by the numbers.

Well...Ashlie said she needed 4x6 so I just went with that but I agree with your approach...

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Old 08-07-2007, 02:25 PM   #10
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steve: If you turn resampling ON, then the image does change along with the white lies.
And as long as you are going to a smaller size, then the lie doesn't get you in trouble...'-}}

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