Increasing DPI for JPEGS

I’ve been using MS Paint to do some simple jpeg editing, but it doesn’t seem to support increased image resolution-- ie, when I shrink a jpeg to a smaller size, the DPI stays the same.

Is there a way to do this in PAINT that I’m missing? If not, is there some decent freeware out there to do this type of image editing? I’m not all that keen about shelling out $$ for Photoshop.

Thanks for the help.

Cannot help you on MS Paint options, but I can point you to GIMP which does most everything that Photoshop does and costs nothing. It is not the easiest software to use, but then neither is PS.

Bad John Mace!

JPEG is a lossy compression algorithm and format. Each time you save your picture, you’re losing information. Always edit and save using a lossless format like BMP or TIFF. Only when you’re finished should you save in a lossy format like JPEG. Now I’m sure that Photoshop will do all you want and more, but I believe a rather cheaper package like Paintshop Pro will more than suffice.

OK, fight my ignorance here. I just download the pics from my camera using the MS camera wizard, and it just does everything for me. How do I get them into a preferred format in the first place?

n.b.: I’m pretty knowledgeable about computers and software, but no next to nothing about image editing. I’m a slow adopter to digital photography, just having bought a digital camera this year.

Assuming you do mean dpi (dots per inch), you can adjust it from your printer dialog box. Low quality -> lower dpi, high quality -> higher dpi. Unless your image is print-quality, though, you’d just be using more dots to print the same low-res image.

If you mean ppi (pixels per inch), though, you’re out of luck. Increasing the ppi reduces the print dimensions while keeping the same pixel dimensions, which crams more pixels into a smaller space and increases the resolution. Paint doesn’t let you change the print dimensions of an image, only the pixel dimensions (I think printing is permanently fixed at 72 dpi) so no, you can’t change it. The GIMP’s free, though.

Another vote for GIMP. The latest version was just released today.

MS Paint is a lousy jpeg editor, in any case, since you can’t even specify the compression.

Arright, just saw your last post. Here’s a quick rundown:

Ppi: How many pixels from your digital image fit in a square inch. One square inch of a 300 ppi image has 300 pixels going one way and 300 going the other. 300 ppi is the standard resolution for most things in professional printing, btw. Assuming you don’t resize your image, the higher you set your ppi, the smaller it’ll end up on paper (obviously).

Dpi: How densely your printer can print images, how many little dots it can cram in an inch (not a square inch, just a line). My printer’s maximum resolution is 9600x2400, which means it can print 9600 dots in an inch going across the page and 2400 going downwards. My last printer’s maximum was, like, 640 or something. Ack.

These two are often confused, but they’re very different things! However, the ppi of an image is limited by the dpi of the printer you’re using the print it - for example if I’d tried printing a 300 ppi image on my horrible old printer… well, I’m not sure how many little dots you’d have to fit in an inch to get 300 ppi but the point is, that printer wouldn’t cut it by a long shot, and the end result would probably be indistinguishable from 72 dpi (or distinguishable only through being very soggy).

So, that should be more than you ever wanted to know, hope it helps.

Also, ran out of edit time (bah) but your camera records the photos you take in jpeg format, there’s nothing you can do about that (well, depending how good your camera is, you might be able to switch it to raw, but you have to “process” the pictures yourself afterwards so if you’re just taking snapshots it’s not worth it). But if you save in the middle of editing, never save over your original jpeg, always save-as in a lossless format, and only save as a jpeg when you’re all done and need a smaller file to show off online or something.

Your question is not entirely clear and I suspect you do not understand some basic concepts which are simple and unrelated to any programs.

An image has an absolute dimension in pixels and that is the most important characteristic. You can double the pixels later but you cannot and will not add one iota of information. You can halve the pixels and you will lose information which will be irretrievably lost. So when you have a photo the most important “size” characteristic is in pixels.

Then some file formats have a field which can specify DPI but this is just a number put in the file and means nothing except as an instruction to print if and when the program wants to follow it. Some file formats do not even have this field. If you take the dimensions is pixels and divide by the DPI you get the printed dimensions in inches. (That’s simple geometry or math or chemistry or something).

Increasing pixels will do nothing for you as far as adding information. If you want to display the image on a computer then you might want to resize it in pixels. If you want it to print in a different size you might want to change the DPI setting. If you want to make the file size smaller then you want to compress it better and maybe reduce the pixel size.

You need to understand the terms so that you can formulate a question which makes sense.

So, having understood all this, can you explain again what you are trying to do?

I can also recommend It is a free replacement for MS Paint, with more features and better editing interface. It isn’t nearly as powerful as Gimp, but on the other hand it’s much less complicated.

Don’t confuse the guy :wink:

If you have a windows box, get “Irfanview”, it is free and it is easy to use, works good and I love it. I also have GIMP on my LINUX box and Irfanview is way easier to use.

Pictures I put up for online viewing I resize to 600 X 400 at about 90% which gives about 60-120 KB’s per picture depending on the picture and that loads fast, even dial-up folks do not get choked up, (great for grandma and aunt Lucy who are way behind but want to see), your cheap friend on dial-up, they upload much faster than the 3000 X 2600 X 567 KB picture that comes out of the camera.

IMO, unless I want to make a high quality print, (which I never do anymore) if someone sends me a huge picture that I have to resize to make it fit on my 1024 X 768 resolution screen, I just delete them. I feel it is as rude as typing in all caps.


An older program called Lview did a few neat tricks real easy but I seldom use it anymore.

I agree that Irfanview is a neat program and I use it regularly for most resizing and compression but it is pointless to mention programs, however good, as an answer to a question which is unclear. The question as asked is unclear and does not really make sense so it needs to be clarified before a meaningful response can be given.

What sailor said (mostly).

Lots of people seem to get confused with dpi and ppi, when all that matters is the size of the image in pixels. I think it would solve a lot of headaches if consumer graphics editors didn’t even show ppi!

From the OP:

The “resolution” of an image on screen is limited by the resolution of your screen, typically 72ppi*. If you view it at a size bigger than that, you’ll see a pixelated image on screen. If you zoom out and view it smaller, you won’t see all the detail. But that isn’t affecting the resolution of the file itself.

As far as I can make out, you’re trying to make the picture smaller without losing any resolution, right? Well that can’t be done, because that means losing pixels, and pixels are resolution.

What you can do is reduce an image so that it is only “screen resolution” (72ppi) at the size you want.

Say you have a 2400 x 1600 pixel image, and you want to appear 6 x 4 inches on your screen. With the current resolution, that’s 400ppi (2400/6 = 400, 1600/6 = 400). But you can’t see 400ppi on your screen; you can only see 72ppi. So the image should still look OK on screen if you reduce it to 72ppi at the target size, i.e. (72 x 6) by (72 x 4) or 432 x 288 pixels.

BUT, that size will be useless for printing. Usually you can reckon on 150dpi giving acceptable prints, and 300dpi for quality photo prints - but your 432 x 288 pixel image would only print at 1.44 x 0.96 inches at 300dpi. Remember, though, those dpi figures are nothing to do with the image file - the file is a set size in pixels, and you set the printer to print at whatever size you want. The dpi on paper will be a function of the print size and the file size, simple maths.

I hope this makes sense…

*72ppi was always “standard screen resolution” when I learnt this - newer LCD screens may be higher than this - check your settings

Hey, thanks for all the great advice!! Yes, I understand the difference between ppi and dpi, even if it didn’t appear that I did. And I understand that to increase the ppi, I need to shrink the image. I’m actually trying to Put together a brochure that will be print quality, and the guy who is doing the printing wants me to have ANY images at 300 ppi, minimum, and preferably at 600 ppi. Does that seem about right?

I downloaded GIMP, and it does the trick nicely. I’ll try IrFanview, too.

Again, the DPI is just a number you can change and it changes absolutely nothing in the actual graphic. It seems to me you want to change the pixel size of the graphic.

So to obtain pixel size you multiply DPI by the dimensions in inches.
so for 3 x 5" @ 300 DPI you would need 900 x 1500 pixels.
As easy as that

Now, taking a smaller pixel graphic and just enlarging it is not going to help with the quality. If you have a 90 x 150 pixel photo enlarging it is not going to make any difference.

I find Irfanview to be best suited for resizing and compression. It works better than most other programs.

If I need to annotate I will use Paint or whatever but then I transfer it to Irfanview for resizing and compression / saving. Each program has its own strengths so I often end up using several.

The best thing for you to do is to change your camera’s settings to save in a lossless format like RAW or BMP or TIFF. Failing that, after choosing the lowest compression setting on the camera, when you transfer the pictures to your computer, use your favourite graphics tool to convert the pictures to a lossless format. Paintshop Pro has a batch conversion mode. Once they’re in a lossless format, then you can start editing.

The best thing for you to do is to change your camera’s settings to save in a lossless format like RAW or BMP or TIFF. Failing that, after choosing the lowest compression setting on the camera, when you transfer the pictures to your computer, use your favourite graphics tool to convert the pictures to a lossless format. Paintshop Pro has a batch conversion mode. Once they’re in a lossless format, then you can start editing.

Got it. Guess I’ll have to dig out my camera’s owner’s manual and slog thru it. I just opened the box and started shooting.

No, you still misunderstand.

Why do you think shrinking the image will increase the resolution? Digital files don’t have a physical size in inches!

Once again, dpi and ppi settings are irrelevant. If the file needs to print at 300dpi, all you need to do is:

  1. Find out what physical size (in inches) the picture will be printed.

  2. Ensure that the file size, in pixels, is at least 300 times this value along each side.

That is it. DPI and PPI are irrelevant!