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Price Printing
Participating Frequently
April 7, 2017
Answered

DPI on enlargements

  • April 7, 2017
  • 2 replies
  • 467 views

Hi, I have a customer who is sending images that are only 2" x 4" @ 300 dpi. They need to be enlarged to 24" x 36". I have tried enlarging via image size using the Resample but have had mixed results. The customer does not understand that the ideal file would be 300 dpi at 24" x 36" or even 72 dpi at 24" x  36". Is there a way I can accomplish this or does the customer just need to supply bigger files. Maybe there's something I'm misssing?

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Correct answer davescm

Try explaining this.
Every square inch in the file she has given you , contains 300x300 = 90,000 dots of picture information, which is why it looks good at 2 inches x 4 inches.

If you enlarge the short side from 2" to 24" (the ratio 2x4 does not fit 24x36), each square inch will contain only 25x25 = 625 pieces of info.

That is less than 1% of the original info making up every square inch. So it cannot look anywhere near as good unless you view it from a considerable distance.

Dave

2 replies

davescm
Community Expert
davescmCommunity Expert
Community Expert
April 7, 2017

You  are (or rather your customer is) asking a lot from resampling - it can achieve good results in the pixels it adds but can't add detail not in the original file.

I would ask for a higher res file.

Dave

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Price PrintingAuthor
Participating Frequently
April 7, 2017

I have been asking but she doesn't even understand DPI and I'm not sure she has any way of looking at the file before she sends it. Basically, I just needed to know that I wasn't doing something wrong. Will show my boss these conversations.

davescm
Community Expert
davescmCommunity ExpertCorrect answer
Community Expert
April 7, 2017

Try explaining this.
Every square inch in the file she has given you , contains 300x300 = 90,000 dots of picture information, which is why it looks good at 2 inches x 4 inches.

If you enlarge the short side from 2" to 24" (the ratio 2x4 does not fit 24x36), each square inch will contain only 25x25 = 625 pieces of info.

That is less than 1% of the original info making up every square inch. So it cannot look anywhere near as good unless you view it from a considerable distance.

Dave

    F
    federico platon
    Legend
    April 7, 2017

    No ay.

    If they need to be printed or used at that size, unless is (scalable) vector art, any images need to be at that size and at the required resolution.

    If they are going to be printed they should be 240-300dpi, 300dpi better.

    If you get smaller sized images, the resolution will be a lot less, unless you upsample... and try to interpolate information that does not exists. Thus you get blurred images, garbage.

    tell your customner that magazine covers do not get pictures from images in web pages, because they use 72dpi, while the magazine requires 300dpi for a quality sharpen image.

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