GIMP Version: 2.8.10
Operating System: Windows
OS Version: windows
GIMP Experience: Beginner Level

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Hey all, I was hoping you could dumb things down to the lowest level possible for me.

I designed a logo for my company to be put on a shirt. But after getting the design to the printer and putting on the design it still had a slight "blur" to it while up close and looked very sharp from a few feet back. Everything I can read up on I did just about everything right. When i created the design I set the document to 300 x 300 PPI. Everywhere I have read is that you want to be at 300 PPI for a high quality image.

The image when I created it was a little over 14 x 14 inches. I sent the image to the printer and they had to reduce it to a little over 12 x 12 inches. No big deal right? It's better to reduce than increase the size of an image in order to keep from getting a "blurred" image, right? Thats what I thought so I decided to make it bigger just in case.

I am just so absolutely confused about this. So I decided to start learning inkscape to help avoid this. However I am reading that inkscape has limits with coloring compared to a "painting" program like gimp. My goal is to start creating concept art that I can put on t-shirts or other medium but I dont know when to use a vector program vs a rastor program and I have no idea how to set the document up at the beginning to get a high quality print out.

Please help! Remember, dumb it down for me. I tend to get lost if too many technical terms are used.

Thanks!

A few scanning tips website has a good explanation of DPI & PPI. What scanning resolution should I use? 300 dpi?
Another good one, PPI vs. DPI: what’s the difference?
This one's easy to relate to, Coming to Terms with DPI, PPI and Size.

Vector graphics can be rescaled freely without any loss of sharpness, and this is important when an image has many hard edges (text, logo...).

PPI is an image definition. DPI is the definition of a rendering technique (printer, display). On inkjet printers a pixel of a given color can be rendered with many dots of the base colors, so the DPI is higher than the PPI.

Okay so what I gather is that when you resize an image either bigger or smaller, you are losing pixels which causes the picture to print out fuzzy, correct?

I thought when you shrunk the image that you actually just made the pixelssmaller which gives you a sharper image or at least retains its quality. Versus enlarging the image which makes the pixels get bigger and this is why the quality suffers. So this is why I figured you could make the original larger and just shrink the image to what size you plan on using.

Now if I understand this correctly I could possibly change the resolution of the image, which would automatically change the size of the printout and not lose any quality?

For example right now my original image resolution is set at 300 and the size is at 14 x 14 inches. I could change the resolution to 335 which will automatically reduce the size to 12.5 x 12.5 inches. This would keep the image from losing any quality right?

Sorry, but after reading the suggestions and watching videos I still just cannot grasp the concept. Honestly I think I get lost in all the terms like "resampling", "Interpolation" and "extrapolating". I just start to get overwhelmed by the industries terms.

Thanks for your patience.

If you scale an image you do not lose pixels, but when you change image resolution you either concentrate or stretch pixel information.
DPI is not used in Gimp or most other graphics programs. Use Gimp Print Size as your guide. Color Management in Preferences is also important and don't forget to include a bleed area.
Yes that will work. You can also just scale or crop image without losing the original resolution.
The important part is to start with at least your minimum resolution. The easiest way is to begin with an A4 or US Letter Template.

This is wrong - you cannot change the size of pixels - each thing you view your image on has a fixed pixel size.



When your image (which is 300x14 = 4200pixels square) is displayed on my monitor it will be displayed as 43.75 inches square because my monitor has a resolution of 96 pixels per inch.

Similarly with printers, the best you can do is the resolution of the printer, so for instance 300 dots per inch. The printer cannot make smaller dots, so you increasing the stated resolution means the printer will have to not print some dots to make it fit your required size, or will have to combine the information from several of your image pixels to decide what colour dot to make.

For example, imagine the colour squares are your image pixels, and the black grid represent the dots your hardware (monitor/printer) can display:


Kevin

Okay, so If I continually make an image larger than I plan on using it, as long its initial PPI is set at 300, I should be okay? Because how will I know later on down the road if I want the size to be different. So starting out by making it bigger I can always reduce the size to a smaller one without losing any quality. Now here is where my confusion sets in... Why did the image get fuzzy after reducing the size?



Perhaps I am understanding things better than I thought but it was the printer that messed up? I sent the file to them in the original size since I was unsure of what they wanted. I figured they could size it correctly. I also sent it to them in PNG format as to retain the transparent background. I remembered they told me the program they used was a CAD program.

Thanks

You will almost always lose some quality when scaling down an image. Imagine you have three pixels of red, green, and blue; if you were to scale those three pixels down to two pixels, there is no way to have those exact same colors in the result. You could discard one of the colors but that obviously wouldn't be very accurate. Alternately (and this is what scaling generally entails), you could alter the colors of the two pixels so that the ratio of red, green, and blue in the image remains the same (e.g., one pixel would be 66% red plus 33% green and the other pixel would be 33% green and 66% blue).


If you are dealing with basic graphical elements such as rectangles, circles, and straight lines then it is best to edit your image at its final resolution (try rendering a checkerboard and then scaling it down to see the loss in quality that otherwise occurs). If you're editing more "natural" images such as photographs or paintings then you might wish to use a higher resolution -- the increased resolution will be of benefit for most filtering operations and this will compensate for the loss of quality when the final result is scaled.

I am a bit confused by this discussion. We cannot reduce the size of a pixel on a given media, but GIMP maintains both the size of an image in inches and its resolution in pixel/in. This creates a virtual pixel size, which can be reduced. In the scale image window, set the width and height unit in inches and set the X and Y resolution in pixel/in. Then, change the resolution upward. The width and height will shrink automatically. This corresponds to reducing the virtual pixel size.