how can I increase the resolution of a picture without resize it?

Question

I want my picture have 300 dpi, but donot change it size. When adjust in Photoshop, it change its size and it is not meet the requirement in my homework. Can you have me?

Answer 1

Most of the other answers miss the relationship of print size to pixel (image) size. and resolution.

When you go to the image size dialog (in Photoshop) look at the pixel dimensions of the top box which is width. Let's just say it is 1000 pixels.

Look at the resolution (towards the bottom) and see what it is in pixels per inch. Lets say it's 200 pixels. That means your print will be 5 inches wide. Get it? Image size divided by resolution = print size.

Okay, so you need 300 dpi (dots per inch, which is for printers) but for here lets say that it is the same as resolution.

Change the 200 to 300.

The 1000 will also change and the 5 inches will stay the same. That's what Photoshop does by default.

Not what you want and easy to fix.

Now just change the Width (top box) back to 1000. The print size will change, but the IMAGE SIZE will be back to the original size.

That's what you want.

In review, so just remember to look at the image size (maybe jot it down), then change the resolution, then go back and change the image size back to its original size.

The description of this is longer than actually doing it.

Resampling does not happen since the image size is the same, so it does not matter if the box is checked.

When you uncheck the box, the pixel dimensions on top are locked by PhotoShop, so you simply change the resolution to 300 and your done. Simpler, yes, but you may not understand the relationship as well at first and not all programs may have this feature. I would use this method once you understand what you are doing.

Answer 2

I don't know if you are having problems keeping the PRINT SIZE the same or the DISPLAY SIZE the same, so I will give you a hint and you can take it from there.

Look under "Image Size." [CTRL]+[ALT]+[I] might take you there. ("i" for "image.")

You will see three boxes at the bottom of the dialogue box: Scale styles, Constrain Proportions, and Resample Image. Different combinations will affect which output is altered when you change the resolution. Try them on and off until you find a combination that keeps the appropriate image the same size.

If you do NOT resample the image (remove the check mark), constrain proportions, and change to 300 pixels per inch, the screen output will be the same, but the print size will change.

If you DO resample the image and still constrain proportions, the print size will remain the same, but the screen size will change.

Answer 3

If you want to change the resolution and not the size, go to image size and change the resolution to 300dpi and make sure the size you want it right eg 4inches by 6 inches. When you click OK it will change the zoom on the image not the actual size. To not change the file size use the 0 to 12 jpeg compression to get the file size the same or close to the original.

Answer 4

it's pretty simple. when you op-en the 'image size' dialogue box, on the bottom there are a few boxes that are probably checked. the one you want to un-check is the 'resample image' box. that's the one the changes your pixels along with the size. if that's unchecked you won't be able to adjust the pixels. you can adjust the size but the pixels will stay the same.

Answer 5

you need to somehow decrease the pixel size of the pic on the computer. That way, if you want to resize it, it will look good. Not all programs have this option.