2 questions regarding output to offset printing

Question

I am using CS4 to work on pictures I have taken and will be used for postcards. The sizes can be 105*148 or 120*170 mm. some cards will have more then one picture in which case there may be samller inserts, maybe as small as 25*25mm
In relation to this work I have basically 2 questions:
1) I will be using Indesign to size the pictures down to final size and also for the small inserts. My question is regarding sharpening. Do I need to size the photos in Photoshop and possibly adjust the sharpening there, or do I not need to worry about this?
2) Should I convert my photos to CMYK in Photoshop, or can I leave this to Indesign? I will be sending the pictures to the printers as PDF.
Much appreciate any help and comments on this,
Tolli Birgisson

Answer 1

Tolli_Birgisson wrote:
I am using CS4 to work on pictures I have taken and will be used for postcards. The sizes can be 105*148 or 120*170 mm. some cards will have more then one picture in which case there may be samller inserts, maybe as small as 25*25mm
In relation to this work I have basically 2 questions:
1) I will be using Indesign to size the pictures down to final size and also for the small inserts. My question is regarding sharpening. Do I need to size the photos in Photoshop and possibly adjust the sharpening there, or do I not need to worry about this?
2) Should I convert my photos to CMYK in Photoshop, or can I leave this to Indesign? I will be sending the pictures to the printers as PDF.
Much appreciate any help and comments on this,
Tolli Birgisson
You can use InDesign to resize the images. When you select an image you can go to Window>Info and it shows you two things
Actual PPI
Effective PPI
Actual PPI shows what resolution the image is itself.
Effective PPI shows you what resolution the image is at it's current scaled size. The larger you make the picture the lower the ppi (or the bigger you make the picture the further the pixels separate and therefore the less PPI (pixels per inch). The same is applied when making the image smaller. The further you reduce the picture, the closer the pixels get to each other, therefore you have more pixels per inch, which is a higher PPI.
The advantage of doing this in InDesign is that you have no second party software to rely on. You just resize.
The disadvantage is that InDesign doesn't apply any sharpening or other filters to the image, it uses Bicubic Smoother (I think?) to resample the image.
When you export to PDF you can choose what way you want to resample images and to what resolution you want images above say 450 ppi to be resampled to 300 ppi.
It would be better to use photoshop to make them the images the correct size at the correct resolution and place the image at 100%. You can then apply sharpening etc. to the image in photoshop. You can turn off resampling the images in Export to PDF in InDesign and turn off compression.
If you are going to resample the images in Photoshop then you should be aware of file types. If they're all jpgs then you don't want to resave your images as JPG, you'd be better of resampling and resizing and then saving the image as a tiff, as it's a lossless format.
You can use CS4 to relink to another folder
Now for question 2
You can convert your images to CMYK in photoshop, why not? Well make sure your Color Settings are set up similar to that of InDesign. If your images are going to be for print only then you can Assign Profile of whatever profile you want. You should check with your printers what profile they use. It could be:
Coated or Uncoated Fogra
US Sheetfed
Euroscale (coated or uncoated)
US Web Press
etc.
You need to check that with prepress.
Of course you can convert your images to a profile when exporting to PDF straight from InDesign. In which case don't convert to CMYK in photoshop - sort of. It's a rather complex answer.
But if you choose the profile Colour Conversion of Convert to "Destionation Preserve Numbers"
Select your Destination (profile, which will be Coated or Uncoated Fogra or US SHEETFED or US WEB Press or whatever was recommend by your prepress in what they use).
As I said it's a rather complex answer so perhaps this will clear up anything else for you, if not just ask http://www.peachpit.com/articles/article.aspx?p=1324238