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I have an jpeg file of 300 dpi. I need to reduce it to 200dpi. How can I do that?

Do I need any specific application or it can be done using Picasa/paint/MS picture manager, if yes how? Thanks

2
  • 2
    For those who are confused about the difference between dpi and resolution, read The Myth of DPI. Apr 10 '15 at 12:13
  • 1
    This question is unclear. Depending on the use case, changing the resolution can mean either keeping all of the pixels and changing the size it will occupy, or keeping the size the same and changing the pixels. I won't vote to close at this point, but readers landing here should understand the difference, and how the solutions relate to their needs.
    – fixer1234
    Nov 28 '18 at 21:45
14

Use Paint.NET

http://www.dotpdn.com/downloads/pdn.html

Go to Image > Resize > Change its resolution (dpi)

As I said the resolution in the Paint.NET is the DPI (pixel/inch)

enter image description here

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  • 1
    Resolution and DPI are different things. Jun 14 '13 at 13:46
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    I just re explained why I said "Resolution", you can see it on the screenshot (pixel/inch)
    – eXshade
    Jun 14 '13 at 13:58
  • 2
    Gave +1 after the update, as it is an important distinction. Jun 14 '13 at 15:08
  • 1
    Paint.NET has the right terminology. DPI is only for printing, not for display on monitors.
    – Karan
    Jun 14 '13 at 23:09
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    I voted this answer but cannot take my upvote away. I think the best way of doing is this is software independent online. See my answer below. Jul 23 '14 at 12:45
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I suggest using GIMP; it is a free image-editing solution, and it allows you to change the resolution, in pixels per inch, in both the x and y dimensions. I believe that this program can accomplish what you are looking for.

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  • 1
    "The image you are loading has 16 bits per channel. GIMP can only handle 8 bit..." GIMP is limited in this regard.
    – Frenzy Li
    Nov 9 '17 at 20:43
  • GIMP supports 16 bits per channel (now). However the OP specified jpeg, and this format only supports 8-bit.
    – AndyK
    Jul 25 at 8:38
4

And I would take this one free tool: http://www.irfanview.com

To change DPI for the currently loaded image, click the "i" icon ("i" for information) on the IrfanView toolbar. Change the DPI, click OK, and save the image.

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    As far as I can tell, this has the unintended consequence of re-compressing the image and losing information. When saving JPGs, the user selects a compression percentage which IrfanView uses to create a new JPG with the new DPI and a new compression. It appears using "Options > JPG Lossless Rotation" with selecting only "Set DPI" still changes more than just the DPI, as when I tested this my filesize increased by ~80KB. The convert-town tool (see other answers) only changes the DPI metadata without modifying other headers or the image; I verified this with the HxD hex editor. Dec 11 '19 at 5:24
4

You can change the DPI of your jpeg image without an application using this free online tool:

convert.town/image-dpi

  1. Enter your new DPI value
  2. Upload your image.
  3. Download the adjusted image.
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I think the best way of doing is this is software independent and without installation processes.

  1. Google online DPI converter
  2. Click First search. For me, the first hit is online-convert.com at the time, but their URLs are time variant so google for them: dpi online-convert
  3. Select file to upload
  4. Change the value of DPI only to 200
  5. Done!
1
  • -1 only works if you are lucky
    – lindhe
    Aug 15 '17 at 20:55
0

For resize an image I use Faststone Photo Resizer. It has an option for DPI.

  • In advance settings you can choose all the settings: resolution, DPI, procentage. It's great.
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  • This appears to be a cool tool. But as far as I can tell, this has the unintended consequence of re-compressing the image and losing information. When saving JPGs, the user selects a compression percentage which FastStone uses to create a new JPG with the new DPI and a new compression. The convert-town tool (see other answers) only changes the DPI metadata without modifying other headers or the image; I verified this with the HxD hex editor. Dec 11 '19 at 5:37
0

I use Faststone Image Viewer https://www.faststone.org/FSViewerDetail.htm. This allows you to set DPI in both X & Y dimensions using the Set DPI command from the Edit menu. This is a lossless change i.e. does not recompress the image.

-1

Don't waste your time, images don't have a resolution (DPI) images are resolution independent

When printing tell the printer what size you wish to print the image and at what quality, then let the printer do the rest

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    Some image formats store a resolution and some don't. That value is used by some applications for purposes like sizing the displayed image on the page.
    – fixer1234
    Jul 13 '15 at 6:25
  • 1
    This answer is just plain wrong.
    – lindhe
    Aug 15 '17 at 20:53

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