What is the best dpi I should use for my images in InDesign for best results

[Augusto24716166az1l]

Hello,

Fairly new to  InDesign here. I've started an online course and checked some tutorials in the last few weeks.

As I start my photobook project one of the first questions in my head is what dpi I should use for my images when creating the book in InDesign.

I have my selection of photographs in 300dpi, 600dpi and some in 1200dpi to choose from. I believe the project will be printed in 300dpi. 

If I want to achieve the best possible quality for these images when printed, which resolution should I be using when importing the images in InDesign? Does it matter or will a 1200dpi image look sharper when printed than a 300dpi one?

I understand I can use different dpis when working with InDesign. Will InDesign convert the entire document to 300dpi when I create the final PDF for printing?

Last question, if I decide to work with 300dpi images, should I resize them in Photoshop or InDesign for best results? Most images will need scaling down to fit the pages/design, I was wonering wich one of the two options is best.

Thank you in advance!

[Eugene Tyson]

It will depend on your PDF output settings - images can be downsampled to whatever DPI you require for printing.

DPI is derived for lithograhic printing - a forumla based on the rotation of a halftone - which a square that is 1x1 on all sides will be 1.41 from tip to tip.

In lithogrpahic printing it's output on with an LPI (lines per inch) and this is where the DPI is derived.

The LPI on lithographic output for newspapers can be anywhere from 80-120

For magazine 120-150LPI

And for higher end books about 200LPI

The 1.41 is multiplied by the LPI - for example 150x1.41 = 211.5 DPI for best/minimum DPI.

If your book is printed digitally - digital printing can be a bit more forgiving as it's not really working with halftones - where it do or simulate it is debatable, but the printing process is completely different to lithographic printing involving screen angles and different plates for each colour (CMYK).

It's erroneous to think 1200PPI will print better because it's higher - the output device might resample images to suit it's output.

The only time it's probably advantageous for 1200 or 2400 PPI is when it's Line Art Drawings.

But for digital it might be irrelevant.

Best answer

Ask your print provider.

They'll probably just tell you 300. 

But you don't have to resample all your images to 300.

Place them into InDesign - and check the Links Panel

It will give an effective resoltluion

When outputing the PDF for print you can downsample the images to 300 DPI for print.

Then images that are too big will be resampled.

[rob day]

Hi @Augusto24716166az1l , When you place a linked image, the Link Info panel will show you the image’s Actual Resolution and the scaled resolution, which is listed as Effective Resolution—a 300ppi image placed and scaled to 50% will have an Effective Resolution of 600ppi. It is the Effective Resolution (the output resolution that matters).

On a PDF Export you can choose whether to leave the output resolution unchanged or downsample to a specified resolution—see the Compression tab. The needed resolution is image dependant, but as a general rule of thumb 300ppi is adequate for most images output for commercial offset printing.

[chrisg11235813]

I agree with @Eugene Tyson .  It is always best to ask the provider directly.  Chances are that 300dpi is standard for a print provider.

From my experience, don't be too critical of the actual number "300dpi",  I've had images that were 50dpi that looked execellent.  I have also been supplied with images at 1200dpi that looked awful.  If the image looks good at 100% final print size (on screen),  it will most likely look the same printed.

However, some on-line "upload and go" print providers don't have actual humans that look at your files, thus no one to make any judgement calls about anything that looks wrong (or right). If you do not follow their strict guidelines, your files get rejected outright, and you are forced to revise and resubmit.

[Augusto24716166az1l]

Thank you for all three replies. Really helpful and I'm clear about the dpi issue.

However, I'm still not clear if I should scale images down directly in InDesign to the desired output size or resize them in Photoshop beforhand? I'm asking because lwhen reading some old forum threads a user mentioned Photoshop has better tools than InDesign for resizing images at the higest quality.

[Eugene Tyson]

As already said you can reample on output from InDesign. 

Some more details.

Insert the image in InDesign

Check window→info

The info panel will show the effective resolution

As long as it's higher the circa 300 then that's fine.

If it's below 250 then it might be a concern.

However for images above 300

When you file→export and choose pdf.

You can downsample through the compression options

[chrisg11235813]

Using Photoshop to downsample, you will get "better" results. There are more options in Photoshop -- different settings for scaling up/scaling down/etc.  inDesign does a good job at the resampling, even for high-end quality.

If you use Photoshop, be sure to save you resized images as a new file, once you resample and save you can't get those pixels back. You will also have to go through the process of resampling anytime you adjust the size of an image within inDesign.  If I were creating the photobook, I'd let inDesign do all of the resampling work.

[Augusto24716166az1l]

Thank you both. Really helpful.

[Eugene Tyson]

Using Photoshop to downsample, you will get "better" results. There are more options in Photoshop -- different settings for scaling up/scaling down/etc.  inDesign does a good job at the resampling, even for high-end quality.

By @chrisg11235813

InDesign uses the exact same resampling as Photoshop.

Only quality you might get is if you need to sharpen, or edit in some way after resampling the image. 

Typically - there is no reason to downsample an image in Photoshop, if you're not making any further edits, InDesign export to PDF does the exact same conversion.

[rob day]

Photoshop has better tools than InDesign for resizing images at the higest quality.

Just to be clear, InDesign resizes an image when you scale it on the page—the pixels are resized not resampled. On a PDF Export you can chose to downsample or not (there is no upsampling), and you can also choose different downsampling quality methods—Average, Subsampling, and Bicubic. Resampling to some exact target resolution would entail significant work, and then you would no longer be able to increase the image’s scale on the page without lowering its Effective Resolution.

Also keep in mind an offset press doesn’t print the actual pixels—the image has to be converted into either a halftone or stochastic screen, which has a considerbly coarser resolution. It’s highly unlikely any subtle quality gain you would get from a Photoshop downsample, if one exists, would be detectable in the screened offset print.