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Increasing dpi/resolution

Aug 23, 2014, 17:42
Post: #1
Increasing dpi/resolution
hello all, i would really appreciate your help, i have used the search function, but i am still not completely understanding. so, there is a company that is printing t-shirts for me. i have to send them images of the exact size as they would appear on the shirt.

before, i was using pixlr, a free online image tool, to resize, make different colors, variations, so forth. i would order samples of the shirts, some turned out great, others looked different from what we thought. as in the colors werent as bright, images could have been a little sharper.

so after i emailed them, they had shown me a screen shot from their computer, and they circled the resolution box and said "your dpi is at 72, it needsd to be a minimum of 150."

so, how can i increase the dpi of existing images? what are my options here? i have recently downloaded gimp, and i am changing the resolution, but i am afraid this is not working, i think it saving the image to a proportional size. it shows it changing the size in inches when i adjust the resolution to a needed value.

however, when i go under scale image, it shows the image as the correct size, and it also shows the res i set previously under the other option. im so lost right now. can i do this in gimp? if not, what are my other options? does photoshop do this? i cannot afford photoshop right now but it may be my only option.

thanks.
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Aug 23, 2014, 18:26 (This post was last modified: Aug 23, 2014 18:31 by rich2005.)
Post: #2
RE: Increasing dpi/resolution
There are a couple of issues here

Quote:..some turned out great, others looked different from what we thought. as in the colors werent as bright, images could have been a little sharper...

The printer almost certainly wants images in CMYK format rather than RGB that Gimp produces. Explore the possibility of creating your designs from scratch (at 300 ppi) using free application Krita.

Quote:..they had shown me a screen shot from their computer, and they circled the resolution box and said "your dpi is at 72, it needsd to be a minimum of 150."

can you share this screenshot with us.

Quote:..how can i increase the dpi of existing images? what are my options here? i have recently downloaded gimp, and i am changing the resolution,..snip.. when i go under scale image, it shows the image as the correct size, and it also shows the res i set previously under the other option. im so lost right now. can i do this in gimp? if not, what are my other options? does photoshop do this? i cannot afford photoshop right now but it may be my only option.

The printing resolution has nothing to do with the image size in pixels, it is just a setting to tell the printer the size for printing. - see the above post for the conversion

This is an image at 72 ppi: http://i.imgur.com/ybZytRw.png
This is the same image with the print size set to 200 ppi, then exported: http://i.imgur.com/uL6XkOA.png

How can you tell the difference? Go into view and un-tick dot-for-dot which will show the comparitive size (zoom level being the same) both images 512 x 512 pix.
http://i.imgur.com/MZeT1Ql.jpg

If your printing co. does not recognise the setting then maybe some other co.?

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Aug 23, 2014, 19:23
Post: #3
RE: Increasing dpi/resolution
(Aug 23, 2014 18:23)ofnuts Wrote:  See Image>Print size to change the DPI. But remember that DPI, pixels and print size are completely interrelated:

Code:
Print size  = pixels / DPI

So increasing the DPI without increasing the size in pixels reduces the print size. Image>Print size won't let you change the size in pixels, so when you change the DPI the print size changes correspondingly.

In the Image>New dialog, if you set a specific DPI and enter the required print size, Gimp will compute the size in pixels for you.

thanks for the response. so, just to make im clear on what you are saying, i cant do it from the print size option without changing the size, which is not an option for me, since my files have to be the exact size that they would appear on the shirt.

what about under the scale option right below? i can change width/height to desired number (which is usually 960 x 960 or 10 x 10 in) and change the desired resolution to the 150-300 range. Is this not what I want? when i have been saving images in the past on pixlr and uploading them to the print shop's site, it is the correct size.

i tried a min ago making the changes like i just described above and exported as png, which are the type of files they prefer. when i hovered over it in the file folder, it showed it as 960 x 960, which to my understanding is 10 x 10 inches. i hope i am doing it right.

also, i did not see image>new dialog under the menu. can it be found somewhere else? thanks.
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Aug 23, 2014, 19:33
Post: #4
RE: Increasing dpi/resolution
(Aug 23, 2014 18:26)rich2005 Wrote:  There are a couple of issues here

Quote:..some turned out great, others looked different from what we thought. as in the colors werent as bright, images could have been a little sharper...

The printer almost certainly wants images in CMYK format rather than RGB that Gimp produces. Explore the possibility of creating your designs from scratch (at 300 ppi) using free application Krita.

Quote:..they had shown me a screen shot from their computer, and they circled the resolution box and said "your dpi is at 72, it needsd to be a minimum of 150."

can you share this screenshot with us.

Quote:..how can i increase the dpi of existing images? what are my options here? i have recently downloaded gimp, and i am changing the resolution,..snip.. when i go under scale image, it shows the image as the correct size, and it also shows the res i set previously under the other option. im so lost right now. can i do this in gimp? if not, what are my other options? does photoshop do this? i cannot afford photoshop right now but it may be my only option.

The printing resolution has nothing to do with the image size in pixels, it is just a setting to tell the printer the size for printing. - see the above post for the conversion

This is an image at 72 ppi: http://i.imgur.com/ybZytRw.png
This is the same image with the print size set to 200 ppi, then exported: http://i.imgur.com/uL6XkOA.png

How can you tell the difference? Go into view and un-tick dot-for-dot which will show the comparitive size (zoom level being the same) both images 512 x 512 pix.
http://i.imgur.com/MZeT1Ql.jpg

If your printing co. does not recognise the setting then maybe some other co.?


Thank you so much. actually, they do want the colors in rbg, i copied and pasted some of their print guidlines here:
Use RGB color space
All colors should be in RGB. Whites should have a rgb value of 254, 254, 254 (See tutorial)
Backgrounds must be transparent
All colors that appear in the artwork will be printed.
PNG files are best
If creating a 150dpi or larger PNG (at actual size) file isn't possible, use other file formats like Photoshop, PDF or TIFF.
Outline your fonts
All fonts in the print files should be converted to outlines so you don't have to send over the font files.


here is the email they sent in response:

Hi Misty!
Please find the color that was submitted to us here: http://screencast.com/t/fERR2HAwY
We could print brighter, however I would recommend to always use pantone colors and use the cmyk code on photo shop: http://www.pantone.com/pages/pantone/colorfinder.aspx
Unfortunately the the dpi is also to low at 72: http://screencast.com/t/7mF8ixUloqgh Our minimum dpi is 150.
Please let me know if I can be of further assistance!
Best,
Jason
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Aug 23, 2014, 20:15
Post: #5
RE: Increasing dpi/resolution
(Aug 23, 2014 19:33)caso81 Wrote:  here is the email they sent in response:

Please find the color that was submitted to us here: http://screencast.com/t/fERR2HAwY
We could print brighter, however I would recommend to always use pantone colors and use the cmyk code on photo shop: http://www.pantone.com/pages/pantone/colorfinder.aspx
Unfortunately the the dpi is also to low at 72: http://screencast.com/t/7mF8ixUloqgh Our minimum dpi is 150.

That sounds like a very reasonable printing company, wish they were all like that.

You have your answer from Ofnuts on image size.

FWIW, Stick to png with a transparent background. For your design, something like that would scale up a little, but best to start with a larger canvas in the future.

Colours
Attached the Pantone palette in Gimp format, pantone.gpl might be useful. It is zipped, so unzip, and copy to your profile palettes folder (for Win) C:\Users\yourname\.gimp-2.8\palettes

Best of luck


Attached File(s)
.zip  pantone.gpl.zip (Size: 6.45 KB / Downloads: 13)

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