How do you change low resolution to high resolution?

Answer 1

Sometimes our customers give us JPEG pictures at 72DPI. Even worst is when these pictures need to be enlarged, ending up with something like 16 DPI…

For the cases where there is no other sources, we have refined a process to be able to print at 720 DPI on our large format printer with satisfactory results, commonly so good that a normal viewer will not discern the difference with a picture originally at 150 or 300DPI.

But let's start with pictures of a real case example that we handled just last week, before giving you the recipe

cropped and zoomed detail of the original picture and improved picture, both zoomed 400% to see the defects on a screen resolution:

Original Picture

And now the same area after our processing

Improved Picture

Quite impressive, right ? And remember this is a 400% zoom i.e. the improved image really have no scales and almost no blur at 100%.

As can be seen, while you can't really generate details that are not in the picture, you still can greatly improve the actual aspect by applying a few simple techniques, trying and choosing them on the final effect you want to achieve.

Here are the details for Photoshop but they should be applicable to others image processing software.

The simpler and usually starting point is to increase the resolution by step [instead of in one time], ex: double from 72 to 144 to let's say 360 than 720, using different smoothing algorithms.

I also recommend to start your process by changing the depth from 8 bits to 16 bits before doing these resolution increased, and to revert back to 8 bits only at the end, right before printing. This should reduce the moire and flat surfaces.

And you can do some final sharpening/blurring and noise reduction/noise addition as the last step[s].

They are also a few plug-ins available that claim to achieve excellent results. I tried them, and while they results are better than just doing a simple pass DPI increase, I prefer my process that allow me to proceed stage by stage and reach my expected level of quality in a more controlled manner.

This will work really nicely for an originally good 72DPI picture, like the example above, and is time intensive, not to mention you need a strong CPU, lots of memory and better a SSD if your picture size is big. So, I do this as part of my preparation process before printing, since I always print files that I have pre-converted to the right resolution, color mod/profile and saved as TIFF, cause I don't trust the RIP engines

If you start with a low quality level JPEG picture than it's a little bit more challenging, you better start by applying JPEG removal artefact algorithms.

This is the kind of thing we do on a daily basis for our customers as part of Plixo's ultra large format printing services, most of the time we don't even tell customers about it but they tend to notice and ask how we manage to get such results

Hope this helps.

Answer 2

You can enlarge the image. In the process you will also loose some of the quality of the image. It is a good practice to use a resizing tool to do it on your computer before sending the image to the printer/photo store. This way you know the result from the very beginning and are able to fine control the resize algorithms.

A tool that may help you in the process is AZImage - see referenced links. I recommend this tool because it allows you to choose the resize algorithm under advanced options and has a trial period.

Answer 3

To convert high resolution photos to a lower resolution:

1. Open the photo for display.
2. Right mouse click on photo.
   • (I have my photo editor set as the standard Microsoft Office Picture Manager, but many other photo display programs also work.)
3. Select edit.
4. Select Re-size, choose desired size, save
5. File Save as...

Answer 4

The best way to decrease the resolution of digital artwork is to open it with Adobe Photoshop. Then go to the top of the screen and click Image > Image Size > and change the number in the box labeled "resolution." Be sure that "Resample Image" is checked so that it will discard the extra resolution, rather than reallocating it. Then Save As, and you're done.

Answer 5

Using a Windows computer, you can right click an empty space on your desktop, and click properties, then click the Settings tab, near the bottom of the window under "Screen Resolution" you will find all the resolutions that your display card supports, use the slide to increase and decrease your resolution.

Answer 6

Yes you can from Image > Image Size. There are two ways to change resolution: if you want to change pixel per inch resolution uncheck Resample Image option and type Resoution you need for print in Resolution field.

For more details and step by step instruction follow related links below.

Answer 7

You can either install "Re-size it!" and re-size your images that way, or import them into iPhoto, email them to yourself via the "Mail" button near the bottom of the screen, then save the images when they get to you. I recommend the first method because it is simpler, and more of a pleasant experience.

Follow the related link to download the "Re-size it!" app. As always, download and install with caution.

Answer 8

If your scanning in a picture to later edit or use in photoshop the best thing to do is use 600 to 800 dpi in the scanner settings and save as a tif.

Answer 9

Use the Image Size command in Photoshop.