DPI for images on book cover??

[6thSense]

I don't know if this necessarily belongs in this forum, but I didn't know where to post. I need a DPI remedial course. I am probably making this harder than what is has to be. Here is my situation. I am designing this book cover, and the image I want to use is on iStock. They give me four options:

425 x 282 px
5.9" x 3.9" @ 72 DPI

849 x 565 px
11.8" x 7.8" @ 72 DPI

1698 x 1131 px
5.7" x 3.8" @ 300 DPI

3504 x 2336 px
11.7" x 7.8" @ 300 DPI

The image only needs to be 380*253 (give or take). In any case, my logic tells me that since this is going to print (book cover), it is better to go higher DPI (thus higher resolution), and scale down? Meaning take the 5.7 x 3.8, edit it, then scale down. Is that train of thought correct?

I guess where I am getting confused is the part where I shrink the image. Say I want to use another image for the spine. Spine images are relatively small, so does the same principle apply? Should I get 300dpi and scale down, or just get the smaller one at 72?

[Virgo Nightingale]

When you say 380x253, I'm assuming you mean pixels. Your printed imagesshould be 300 dpi, so after hitting the calculator and dividing by 300, the image itself would be 1.26" by 0.84"? If that's the case, you can use one of the smaller images and just change the resolution to 300 dpi in PS (with Resample Image UNchecked). The pixel information won't change, just how many pixels will fit per inch.

[tZ]

if its offset then you need at least 300dpi.

If you printing digitally you need at least 150dpi.

The general rule is you can allows go smaller but, not larger without sacrifing either the size or resolution. For example, a 20 x 20 image at 150dpi can be scaled to 10 x 10 and that will make it 300dpi. You could also go up and scale it to 40 x 40 but, that would make is 150/2 = 75 dpi. The scaling factor is around here somewhere. If you search scaling factor on this forum there is a big discussion on this. The higher the resolution the better.

[tZ]

theory behind it all:

http://pic5.picturetrail.com/VOL90/2128115/9444892/134831188.jpg

http://pic5.picturetrail.com/VOL90/2128115/9444892/134831192.jpg

reference thread:
http://www.graphicdesignforum.com/forum/showthread.php?t=15058&highlight=increase+image+size

[6thSense]

Thank you guys. That answered my question. I am definitely saving this!!

[PrintDriver]

Wow, talk about convoluted and slightly impractical tZ...LOL. But you do get there eventually...assuming you are scanning a 5x7 color transparency on a drum scanner, not actually starting with a digital file. Trust me you aren't going to be taking a 5x7, 300dpi digital image up to 180"h. Or scanning a photo on a flatbed either. Or printing something that big at 300dpi :D ya, ya, illustrative purposes.

[6thSense]

Wow, talk about convoluted tZ...but you do get there eventually...assuming you are scanning a 5x7 color transparency on a drum scanner, not actually starting with a digital file. Trust me you aren't going to be taking a 5x7, 300dpi digital image up to 180"h. Or scanning a photo on a flatbed either. :D


To be honest, I am at work and...heck, blame it on lack of sleep. lol. Was up late last night watching Fracture with the Mrs.

I believe I need it at 380 x 253. I can't remember the exact size. I dunno where I came up with the 5x7. Sorry.

[PrintDriver]

No I was talking to tZ... I'm sorry for the pseudo-hijack.
You do understand the difference in resolution using pixels as opposed to inches yes?
How big is the image going to be on your book cover in inches?

[Virgo Nightingale]

You mentioned that one of the photo size options iStock gave you was a 5.7" x 3.8", but I think PD was just commenting on tZ's example.

[PrintDriver]

In pixels 380 x 253 is about 5"x3.5"
However when you say 380 pixels you are talking at <usually>72dpi or pixels per inch in this case.
For a 300dpi image you would need to use the 3rd option in the list to cover your resolution needs. So you really need at least 1698x1131 photo. I can't make this make sense if you don't understand the relationship between pixels and 'dpi'...

[6thSense]

hmmm. Man, I would have to be at home with Illustrator up. It is a 6x9 book, and the image will be approximatley.......I dunno, 2.5 inches wide maybe?

This will be the image I will use (minus the font). Well, the font will be there, but not the font listed. See, I posted it in another forum to get tips for techniques to make the text appear like the newspaper article, and this one guy tweaked it (as shown).

So to answer your question, I don't want it to consume the full back, just a portion. However, I do want the font to be legible (when I am complete).

That make sense?

[PrintDriver]

The other problem you may encounter is that if you are working in pixels and you don't have the right file resolution to start with when you open your starting file in Photoshop, you may inadvertently start at too low a res and all items brought into that file will have the same low res.

[tZ]

lol

I made that a long while ago but, yeah.

That one time I forget at least its hear instead of digging through my thousands of folders with no relevant names once so ever,lol.

[6thSense]

The other problem you may encounter is that if you are working in pixels and you don't have the right file resolution to start with when you open your starting file in Photoshop, you may inadvertently start at too low a res and all items brought into that file will have the same low res.

Starting at 300 should be ok though, right? For the size I am estimating?

[bluekivi]

Always use the highest res file that you can get your hands on (within reason). It gives much better quality even if you downsample a little rather than up-rezzing. I strongly discourage up-rezzing any image.

[Drazan]

I have to disagree. You will waist money buying a 3504 x 2336 px, 11.7" x 7.8" @ 300 DPI file when you only nee this one.
1698 x 1131 px
5.7" x 3.8" @ 300 DPI

You always want to work with the exact DPI that you are going to print. Whether this is at a scale or full size.

Here is a nice online converter to calculate what size you need exactly.
http://www.classical-webdesigns.co.uk/resources/pixelinchconvert.html

You will also want to resize the photo before you place it in your document. For example if the file is 300dpi but to large and you place it directly into your work document you may inadvertedly resize it to the size you need, but have a 600dpi image.

What you don't want to do is upsize a low res 72dpi image and expect it to print as clear as a 300dpi image. It won't work. You will still end up with just as much fuzziness as the 72dpi image. Same thing if you have a smaller 300dpi image and you enlarge it. The image will drop in dpi.

Jade

[tZ]

I agree with Drazan.

Get what you need to full-fill the needs of the job and don't go overboard so you reduce cost.

Increasing the resolution or size of any file is fine as long as you know what your doing and the minimum output requirements of the printing process your going to.

[Alan G]

6th, there is a confusion of terminologies here, and it can really mess you up.

The SIZE of the image (in the iStock data) means the nominal size in inches based on the ppi (pixels per inch) setting that's embedded in the file's metadata. It's how big the image will be when displayed (or printed) at that number of dots per inch.

The RESOLUTION of the image is how many dots by how many dots. That's all it is. We often talk about "screen resolution" and "print resolution," but that just muddies the whole issue. For our purposes, the resolution is how many dots by how many dots. A "High resolution image" is one with lotsa dots. A "Low resolution image" -- it's underprivileged in the dot department.

You can change the "size" of an image by altering the ppi setting. A 300 pixel (dot) wide image at 100 ppi is 3 inches wide (300/100). The same exact image at 300 ppi is one inch wide. The resolution hasn't changed. It's still the same number of dots.

So all you need to know is your final output size and dpi. If the image will be one inch wide at 300 dpi, you need an image that's 300 pixels wide. One inch at 300 dpi = 300 dots = 300 pixels. It's NOT "300 pixels at 300 dpi" -- it's just "300 pixels."

You can completely ignore iStock's "@72 ppi" and "@300 ppi" dimensions. They have no effect on the final outcome. They're only there because low-res images tend to be used at screen resolution (nominally 72 ppi) while the higher res ones are usually for print. I guess they're trying to be helpful to the arithmetically challenged. (Most stock houses do it similarly.)

[bluekivi]

I did say (within reason)! As long as you dont up-rez. You cannot get more detail out of a set of pixels, it just averages them out.