In Acrobat 9 the preflight profile Magazine Ads has flagged up the alert in the attached screenshot. The warning "Resolution of color and gray scale images is lower than 300 pixels per inch" turns out to include the match "Color image... 300.0123 ppi". What is happening?
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Resolution "lower than 300 ppi"
- Thread starter leszczuk
- Start date
eugenetyson
Technical User
Tell them to ignore it. For printing purposes you only truly need 225 dpi to print at 150lpi. That is you only need 1.5 x lpi for the correct resolution. And 1.5 x 150 is 225 dpi.
Most prepress places flag images under 300 dpi because it's a standard. But truly you can go as low as 225 dpi without seeing any difference. If your print is for a art magazine or something that uses 175lpi then your resolution should be 265 dpi and it would be sufficient for printing purposes.
In fact, if your image is a blurry gausian or a drop shadow or something then you can go as low as 150 dpi, because detail wouldn't matter that much.
But if your image is a sharp image, like a building, or something with a lot of detail, then 300 dpi is a safe standard.
But again, it's not that much of a difference to 225 dpi, simply because the square root of 2 is 1.414 (to deal with rotated pixels at 45 degrees) that is where the sum of 1.5 x lpi comes from, but who wants to multiply by 1.414? So just round to 1.5.
Remember, it is extremely important to know what lpi you're printing to, and the printers can tell you that information.
Most prepress places flag images under 300 dpi because it's a standard. But truly you can go as low as 225 dpi without seeing any difference. If your print is for a art magazine or something that uses 175lpi then your resolution should be 265 dpi and it would be sufficient for printing purposes.
In fact, if your image is a blurry gausian or a drop shadow or something then you can go as low as 150 dpi, because detail wouldn't matter that much.
But if your image is a sharp image, like a building, or something with a lot of detail, then 300 dpi is a safe standard.
But again, it's not that much of a difference to 225 dpi, simply because the square root of 2 is 1.414 (to deal with rotated pixels at 45 degrees) that is where the sum of 1.5 x lpi comes from, but who wants to multiply by 1.414? So just round to 1.5.
Remember, it is extremely important to know what lpi you're printing to, and the printers can tell you that information.
- Thread starter
- #3
eugenetyson
Technical User
Just ignore it, or set your device to look for images below 299 dpi? Clearly the program is flagging it because of the obscure .00000 discrepency. Perhaps it sees the odd dpi as a problem, or indeed just miscalcuated it. It's a computer program.
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