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reduce resolution while retaining image size on computer

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2015-08-06 18:21:18 UTC (about 3 years ago)
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reduce resolution while retaining image size on computer

Hi,

This topic has been asked and answered several times before, but it doesn't work for me. I want to reduce resolution but keep the same image dimensions on the screen - this has nothing to do with wanting to print.

So I followed the answer given here http://www.gimpusers.com/forums/gimp-user/15189-resolution

I

1) check the cubic or sinc option in quality box 2) changed the resolution, in this case from 600 to 300. 3) re-enter original width in width box 4) click scale image

When I do this, the image DOES NOT stay the same. It shrinks to 50% of original size. What mistake am I making?

Thank you

Chris

Kasim Ahmic
2015-08-08 08:30:51 UTC (about 3 years ago)

reduce resolution while retaining image size on computer

Don't worry about the resolution of the image. Just worry about the dimensions. Scale it down to whatever you'd like and then scale it back up to the original dimensions. Like so:

1. An image is 500px x 500px 2. Scale it down to 250px x 250px
3. Scale it back up to 500px 500px

That right there will half the quality, making each pixel of the scaled down 250px x 250px image take up four pixels instead.

I hope this is what you needed!

- Kasim

Sent from my iPhone

On Aug 6, 2015, at 8:21 PM, chrislz wrote:

Hi,

This topic has been asked and answered several times before, but it doesn't work for me. I want to reduce resolution but keep the same image dimensions on the screen - this has nothing to do with wanting to print.

So I followed the answer given here http://www.gimpusers.com/forums/gimp-user/15189-resolution

I

1) check the cubic or sinc option in quality box 2) changed the resolution, in this case from 600 to 300. 3) re-enter original width in width box 4) click scale image

When I do this, the image DOES NOT stay the same. It shrinks to 50% of original size. What mistake am I making?

Thank you

Chris

-- chrislz (via www.gimpusers.com/forums) _______________________________________________ gimp-user-list mailing list
List address: gimp-user-list@gnome.org List membership: https://mail.gnome.org/mailman/listinfo/gimp-user-list List archives: https://mail.gnome.org/archives/gimp-user-list

Liam R E Quin
2015-08-08 22:14:22 UTC (about 3 years ago)

reduce resolution while retaining image size on computer

On Thu, 06 Aug 2015 20:21:18 +0200 chrislz wrote:

1) check the cubic or sinc option in quality box 2) changed the resolution, in this case from 600 to 300. 3) re-enter original width in width box 4) click scale image

When I do this, the image DOES NOT stay the same. It shrinks to 50% of original size. What mistake am I making?

How are you viewing the image? If it's for use on the Web you'll need to use CSS width and height, or width and height attributes on an img element, to make the Web browser stretch the image to the size you want. The results of doing this are often pretty awful, by the way.

Liam

Thank you

Chris

--
chrislz (via www.gimpusers.com/forums) _______________________________________________ gimp-user-list mailing list
List address: gimp-user-list@gnome.org List membership: https://mail.gnome.org/mailman/listinfo/gimp-user-list List archives: https://mail.gnome.org/archives/gimp-user-list

Liam Quin - XML Activity Lead, W3C, http://www.w3.org/People/Quin/
Pictures from old books: http://fromoldbooks.org/
Kasim Ahmic
2015-08-08 23:45:21 UTC (about 3 years ago)

reduce resolution while retaining image size on computer

Eh, if he's just trying to drop the quality by keeping the same size, it's best to just scale the image down and back up again with no interpolation. Like you said, using CSS would look awful cause all browsers will scale the image up with interpolation unless he wants to use an HTML canvas and use tricks there but that's not even worth the hassle.

- Kasim

Sent from my iPhone

On Aug 9, 2015, at 12:14 AM, Liam R E Quin wrote:

On Thu, 06 Aug 2015 20:21:18 +0200 chrislz wrote:

1) check the cubic or sinc option in quality box 2) changed the resolution, in this case from 600 to 300. 3) re-enter original width in width box 4) click scale image

When I do this, the image DOES NOT stay the same. It shrinks to 50% of original size. What mistake am I making?

How are you viewing the image? If it's for use on the Web you'll need to use CSS width and height, or width and height attributes on an img element, to make the Web browser stretch the image to the size you want. The results of doing this are often pretty awful, by the way.

Liam

Thank you

Chris

--
chrislz (via www.gimpusers.com/forums) _______________________________________________ gimp-user-list mailing list
List address: gimp-user-list@gnome.org List membership: https://mail.gnome.org/mailman/listinfo/gimp-user-list List archives: https://mail.gnome.org/archives/gimp-user-list

--
Liam Quin - XML Activity Lead, W3C, http://www.w3.org/People/Quin/ Pictures from old books: http://fromoldbooks.org/ _______________________________________________ gimp-user-list mailing list
List address: gimp-user-list@gnome.org List membership: https://mail.gnome.org/mailman/listinfo/gimp-user-list List archives: https://mail.gnome.org/archives/gimp-user-list

2015-08-13 00:27:10 UTC (about 3 years ago)
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reduce resolution while retaining image size on computer

Eh, if he's just trying to drop the quality by keeping the same size, it's best to just scale the image down and back up again with no interpolation. Like you said, using CSS would look awful cause all browsers will scale the image up with interpolation unless he wants to use an HTML canvas and use tricks there but that's not even worth the hassle.

- Kasim

Sent from my iPhone

I think I may have figured out the answer. What I'm trying to do is the equivalent of taking a screen grab of a 15mb tiff image, which turns it into a obviously lower quality tiff image of the same dimensions. Is the equivalent of achieving this with gimp to simply reduce the dimensions and then use the zoom function to enlarge the smaller picture? Is that effectively what "Grab" does?

Thank you

Richard
2015-09-06 18:29:41 UTC (about 3 years ago)

reduce resolution while retaining image size on computer

I was about to suggest the same thing. GIMP only ever displays the image onscreen relative to its raw image pixels and zoom % (ignoring any physical print resolution / dpi). If all you do is change the print resolution of your image, the image's size and data (in pixels) remain unchanged, thus there is no visible change in how GIMP displays it. Conversely, any time you resize/scale the image itself -- even if you also change the resolution to maintain a fixed print size -- the image as seen in the GIMP window obviously changes, because it's displayed relative to image pixels and zoom % only.

An option to adjust GIMP's current zoom level to reflect changes in the current print resolution might be an idea here -- the least obtrusive method could be just a checkbox ("Zoom to new size" or something) on the Scale Image and Print Size dialogs....

-- Stratadrake strata_ranger@hotmail.com
--------------------
Numbers may not lie, but neither do they tell the whole truth.

Date: Thu, 13 Aug 2015 02:27:10 +0200 From: forums@gimpusers.com
To: gimp-user-list@gnome.org
CC: notifications@gimpusers.com
Subject: [Gimp-user] reduce resolution while retaining image size on computer

I think I may have figured out the answer. What I'm trying to do is the equivalent of taking a screen grab of a 15mb tiff image, which turns it into a obviously lower quality tiff image of the same dimensions. Is the equivalent of achieving this with gimp to simply reduce the dimensions and then use the zoom function to enlarge the smaller picture? Is that effectively what "Grab" does?

Thank you

-- chrislz (via www.gimpusers.com/forums) _______________________________________________ gimp-user-list mailing list
List address: gimp-user-list@gnome.org List membership: https://mail.gnome.org/mailman/listinfo/gimp-user-list List archives: https://mail.gnome.org/archives/gimp-user-list