How to turn low res image to high res in Illustrator

[Horst...@adobeforums.com]

Hi All,

I am at work sweating over this problem of mine:

I got this image saved as .psd (CS2) that I want to use in a leaflet as an illustration.

I open the .psd file in illustrator and place it on my artwork. Then I discovered that the image has jagged edges after printing, and now I want to change it to a vector graph because I somehow think that it will render better resolution of the image when printing it.

Am I completely on the wrong track here?
How do I make this image become crystal clear and ready for print?

HELP!

Horst Olsen

[Philip_...@adobeforums.com]

Sort of the wrong track.

If it is already jaggy then even if you use one of the vectorizing (live trace) tools in Illustrator it will faithfully reproduce the jaggies.

Depending on how simple the file is, you might lock the .psd file down and trace over it with the pen tool. Or you might go back to the .psd file, and both increase the resolution and perhaps add some gaussian blur in an attempt to smooth things out, then bring it into illustrator.

[David...@adobeforums.com]

I am sure this will seem like a very elementary question, but here goes. What is the fundamental difference between Hi-Res and Lo-Res images? Does the particular format that it is saved as have alot to contribute to this distinction?

[Jacob...@adobeforums.com]

David,

Hi-Res and Lo-Res images refer to raster images, being a woolly way of stating difference in resolution, on other words PPI (DPI in print), only relevant when placing/exporting raster format. Some raster formats can have different resolutions.

[Gernot_...@adobeforums.com]

Quality raster images are mostly saved as TrueColor
TIFFs.
An image doesn't have a resolution, but px pixels
in horizontal direction and py pixels in vertical
direction.
Photoshop may tell you, it has 72 ppi.
Please ignore this - the geometrical size of the
reproduction isn't a feature of the image file.

Put the image virtually onto a piece of paper.
Aha, now it has a width, e.g. 5 inches.
For px=1000 it has 1000/5 = 200 pixels per inch
(ppi).

Recommended standards:
Offset printing: about 300 ppi
Large format inkjet: about 200..300 ppi
Mental calculation accuracy is sufficient.

What happens if the image has far too many pixels ?
Modern RIPs don't degenerate the print quality
(as tested), but the speed is slowed down.

Therefore: save doc as PDF with
Compression: None
Downsampling: 300 ppi if above.

Personally I'm using '288 ppi if above',
because then a PDF can be viewed for zoom 400%
pixel-synchronized, if the setting in Acrobat
is 72dpi (by default it's since Acrobat6 96dpi,
but before it was 72dpi).

Best regards --Gernot Hoffmann

[Spiral...@adobeforums.com]

I am having a problem that may fit in this arena - I am trying to create an avatar for a website that is 50x50 px but not more than 15K ~ I've created it in Illustrator CS and moved it to PS to change it to a jpeg format, but can't figure out the resolution i need to use to get it to be the parameters I need as it always seems to be over the 15K even though I keep brought the resolution down to 72 ??? I have this fundamental block in my head about this issue, sizing and resizing from AI to non-vector programs ~ read all the tutorials I can find but still has not sunk in :( Help it appreciated!!! O_O

[Stephe...@adobeforums.com]

Spiral:

What happens when you File> Save for web> jpg in illustrator? Try the different compression qualities. Also, if it is a relatively uncomplicated drawing and not an image (photo), why not save a gif for web from Illustrator.

steve

[Tim...@adobeforums.com]

Spiral,

Steve's approach is probably the best way to go, and I suspect what you want is to save as GIF with a limited # of colors to reduce file size. I want to add to what Steve said, because I think there's filling in the blanks that might help you...

With any raster image you have a set number of pixels (50x50 or 250 total in your case). When you assign a resolution (72ppi, 150ppi, etc) you are simply telling the image how much or little you want to strech those pixels out over a given area, BUT any way you slice it, you still have the same number of pixels.

In other words, a 50x50 image at 72ppi would theoretically be 0.7x0.7", and the same image at 150ppi would be 0.33x0.33". But there are still the same number of pixels in either case. The ppi/dpi is used for formatting the image for a specific use (ie. 72ppi for on-screen, 300ppi for quality printing). Changing the ppi doesn't change the actual size of the image, unless the number of pixels change too.

Next point is there are several factors that determine the size of an image on disk aside from the shear number of pixels it contains. The two main factors are compression and color information. Some filetypes compress images (JPG for example) to save space, and others might limit the number of colors present in the file (GIF for example).

I think you should do some research to find out what different file types are used for, and read the Illy help section on exporting images for web use.

[Jacob...@adobeforums.com]

Maybe Spiral feels encircled. Spiral Flame, "resolution for commercial" #7, 17 Jun 2007 4:09 am </cgi-bin/webx?14@@.3bc41075/6>

[Spiral...@adobeforums.com]

Thanx to all that have helped clarify this in my head - I understand pieces of this yet putting it all together for a certain outcome sometimes is a bit perplexing - I am going to try all of the suggestions above and hope to learn from it - i REALLY appreciate you efforts!!! ~O_O~ Thanx again - with perserverence (sp??) I'll get it eventually ~