A

Anonymous

Answered

Best image format for InDesign

Forum|Forum|15 years ago
August 25, 2010
3 replies
36021 views

When I've finished editing an image in photoshop, what is the best format to retain quality when I'm ready to export to InDesign?? I'm not altogether worried about document size. Also, how do I export my finished document to a PDF to send to the printer?

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Correct answer Peter Spier

jiyasa wrote:
K, let me see if I got it right...in Image> Image Size, when the image size dialog box comes up in the pixels/inch set it to anything 300 or below. Could you elaborate on the bleeding? Do I just pull any element on my page 1/8" off the page completely or just 1/8" outside the margins to do this? (I'm trying to make sense of this bleeding/slug thing).

WHOA.

Image size is controlled by the capture (camera or scan), and while you can change it in Photoshop, the size you save at is essentially irrelevant. What counts is the "effective" resolution, that is the resolution at the printed size after scaling on the page. If you save an image 4 x 6 inches at 150 ppi, then scale it to 50% (2x3 inches) when you place it in ID, the effective resolution will be 300 ppi. If you scale it to 8 x 12 the effective resolution becomes 75 ppi and it will probably look like crap in print.

Setting a resolution in Photoshop WITHOUT reampling does not affect the pixels in any way, or the effective resolution when the image is placed, only the preview that is saved with the image. On the other hand, changing the resolution WITH reampling means you are either throwing away data (making the image smaller), which is fine if you don't expect to need the image at a larger size in the future, or making up new pixels out of thin air by interpolation (enlarging), and that seldom works out for print.

The suggestion to reduce image size to 300 ppi is related to the PDF export settings. There you have the opportunity to downsample images during the export process when the effective resolution is higher than necessary, which speeds processing at the printer.

Bleed refers to color that extends beyond the trim of the page, so yes, you pull any element that touches the page edge out an additonal amout for bleed. This allows for misalignements in trimming and prevents a thin white border along the edge if the cut is a little off. Slug is an additioanl aree which you can use to put special infrormation that might be useful for the printer, but should not appear onthe final print. It is outside the bleed area and is always trimmed off.

A

Anonymous

Technically, resolution originated when drum scanning came along and was recognized as pixels per mm, multiplied by 25.4. When the MAC came along, it was redefined with a good nuff approach to say the res should be x2 of the line screen printing. Below is how it came to be.

Screen Print - 45 LS Res 6 x 25.4 = 152.4

Newsprint 85 - 120 LS Res 8 x 25.4 = 203.2

Offset 133 LS Res 10 x 25.4 = 254.

Offset 150 LS Res 12 x 25.4 = 304.8

Offset 175 LS Res 14 x 25.4 = 355.6

Offset 200 LS Res 16 x 25.4 = 406.4

Now you see how the resolution so closely resembles the line screen x2. This is how is came to be.

A

Anonymous

"This is how is came to be."

Hate to nitpick, but since this post purports to give a historical perspective I guess an added comment can't really be too late to be relevant.

I would like to point out that the equations given are nothing more than conversions from millimetres to inches and so do nothing at all to explain the origination of the resolutions. Since each LS targetted is dots per inch the resolution must be expressed per inch as well to be relevant. So while these equations show that the most common line screens require approximately 2x the line screen, they don’t say why other than that was the conventional wisdom.

But that convention has not gone unquestioned. A reasonable resolution can be a low as 1.41 times the LS for people and softer images, increasing with the complexity of the detail in the image. It should also be noted that Adobe PostScript RIPs set an image resolution limit of 2.5 times the halftone frequency. Providing any more than that will result in useless processing to reduce the oversampling ratio to 2.5 or less, thus the values stated for Screen Print and Newsprint which are at ratios of 3.38 and 2.39 respectively would technically never be output in most modern RIPs.

BobLevine

Community Expert

May I suggest a good book? Sandee Cohen's Visual Quick Start Guide is a must for InDesign newbies. Less than $20 at Amazon: http://amzn.to/bCCrnS

Bob

A

Anonymous

Thank you, sir! I'll look into that.

E

Eugene Tyson

Community Expert

May I suggest this free one too - http://www.adobe.com/designcenter/cs3/articles/cs3_printguide.html

Page 55 onwards discuss file formats.

While someone said TIFF and PSD, this is true, but beware that both TIFF and PSD can only OUTPUT raster. So if you have text layers, vector shapes or vector masks you are better off saving as a PDF - and you can retain layers in the PDF and Photoshop Editing compatibility.

macinbytes

Inspiring

TIFF

PSD

Others will be around shortly for an image format holy war. As your printer for a .joboptions file for Acrobat and their bleed expectations. Generally .125" bleed on bleeding documents and downsampling images to 300ppi or not downsampling at all is standard. Embedding all fonts is a must. Check with your printer.

A

Anonymous

K, let me see if I got it right...in Image> Image Size, when the image size dialog box comes up in the pixels/inch set it to anything 300 or below. Could you elaborate on the bleeding? Do I just pull any element on my page 1/8" off the page completely or just 1/8" outside the margins to do this? (I'm trying to make sense of this bleeding/slug thing).

Peter Spier

Correct answer

Community Expert

jiyasa wrote:
K, let me see if I got it right...in Image> Image Size, when the image size dialog box comes up in the pixels/inch set it to anything 300 or below. Could you elaborate on the bleeding? Do I just pull any element on my page 1/8" off the page completely or just 1/8" outside the margins to do this? (I'm trying to make sense of this bleeding/slug thing).

WHOA.

Image size is controlled by the capture (camera or scan), and while you can change it in Photoshop, the size you save at is essentially irrelevant. What counts is the "effective" resolution, that is the resolution at the printed size after scaling on the page. If you save an image 4 x 6 inches at 150 ppi, then scale it to 50% (2x3 inches) when you place it in ID, the effective resolution will be 300 ppi. If you scale it to 8 x 12 the effective resolution becomes 75 ppi and it will probably look like crap in print.

Setting a resolution in Photoshop WITHOUT reampling does not affect the pixels in any way, or the effective resolution when the image is placed, only the preview that is saved with the image. On the other hand, changing the resolution WITH reampling means you are either throwing away data (making the image smaller), which is fine if you don't expect to need the image at a larger size in the future, or making up new pixels out of thin air by interpolation (enlarging), and that seldom works out for print.

The suggestion to reduce image size to 300 ppi is related to the PDF export settings. There you have the opportunity to downsample images during the export process when the effective resolution is higher than necessary, which speeds processing at the printer.

Bleed refers to color that extends beyond the trim of the page, so yes, you pull any element that touches the page edge out an additonal amout for bleed. This allows for misalignements in trimming and prevents a thin white border along the edge if the cut is a little off. Slug is an additioanl aree which you can use to put special infrormation that might be useful for the printer, but should not appear onthe final print. It is outside the bleed area and is always trimmed off.

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