Best PPI for Creating New Image in Photoshop

Question

Hi,
Bunch of questions - all in BOLD. I am somewhat new to CS5 and have been playing around with making art in it. Yesterday I created a piece of art simply by selecting 6 inches by 6 inches in the dialog box (because I was thinking of just printing it out at home and gluing it to a 6 x 6 canvas). It defaulted to 72 ppi / RGB as it always does, and I was fine with that when I started the piece and also because I post these pieces of art to my blog on the web.
I am in the process of trying to create art for licensing and understand I will have to create things in CMYK for that (right?). I also understand that I should probably create a PS piece at 300 ppi (or is 355 ppi the new standard?)
I want to create the art on 12 x 12 photoshop windows ("scrapbook size") for manufacturers that will also allow the art to be sampled up and down a little bit (say down to 8 x 8 and up to 20 x 20). Is 300 dpi the best dpi, then, to create the piece at?
Also, is it possible to re-save the file for the web at 72 dpi / RGB for posting to my blog? What is the best way to do this?
Final question, I think, is that I will be printing out my art on my own home printer (4-color HP Vivera inks) for trade shows just to show it and am not concerned that it be the absolute-best of all possible prints. Just a pretty good rendition of it for display purposes and I obviously don't want to go through a boatload of ink and spend 20 years waiting for it to come out of the printer, etc. Can anyone recommend the best setting (CMYK? PPI???) for home-printing of 12 x 12's as such?
Thanks!

Answer 1

that all of these choices will allow me to save it as a copy?
When using Image > Image Size I would recommend duplicating the Image (Image > Duplicate) first to avoid the risk of overwriting the original.
I guess what you are saying is that the manufacturer is able to fiddle with CMYK values that he/she needs and I shouldn't worry about it and just create it in RGB.
Unless you know what space the actual print will be in you better stay in the larger gamut (as most RGB-spaces are likely to be in relation to most CMYK-spaces).
And even if you know the target-space working in RGB offers some advantages and avoids the risk of overshooting the allowed Total Area Coverage (as can happen when working in CMYK-files).
what would be the best way to go about trying to decide what possible CMYK profile I should use, and where in the program would I choose to set it and view it
• Where do you work (North America, Europe, Asia, …)? In Europe FOGRA sets the standard (ISO Coated v2 for sheet fed offset presses at current for example), in other regions of the world different standards may apply.
• What is the likely output for your images (Posters, newspapers, magazines, offset or gravure print, t-shirts, …)?
One can always ask one’s print provider which icc-profile fits their process.
You can use Photoshop’s soft proofing capabilities to get a preview of whatever color-space you find out to be the pertinent one under
View > Proof Setup > Custom
and save that. Then turn View > Proof Colors on or off as needed (command-Y).
But here (as with separation in general) you may want to look into the various Render Intents.
Additionally you can use View > Gamut Warning (command-shift-Y).
can I safely assume when I purchase a scanner and use that in the creation of some work that I should scan things in at 300 ppi?
300ppi effective resolution that is – this means that if you are likely to upscale an image in a layout program like Indesign or just print it out bigger you should do the scan accordingly bigger or with higher resolution so that in the end 300ppi are maintained for products that are likely to be viewed at or less than an arm’s distance.