Upsize and up resolution - - possible?

Brumble Buffin
over 8 years ago

I downloaded a border design which came in at just 32x30 dpi. Went to Bitmaps>Resample and changed size to 8"x10" resulting in a very grainy result. The pixels are everywhere. I set the Resolution at 300, but it didn't help. Do I understand correctly that if I upsize this download, I can't expect a sharp lines result? Is there a way to sharpen this project, or is there not enough pixels to give me the 8x10 inch size I need?  Thanks!

  • 0 over 8 years ago
    Is it possible to go back to the download page where you got the file and look for a "hi res" version? Can you point us to the file?
  • 0 over 8 years ago
    Hi Brum,

    In general, you can not expect a sharp line result if it's a bit map (raster) image. Vector images can be set to any size.
    Think of the pixels as tiles. By simply upsampling, you still have only 32 x 30 tiles of information in an 8" x 10" image. Information is not added. An original tiles is simply replaced by multiple tiles which are almost identical in appearance.

    However, I have found that for some images you can improve matters. It depends on the image. Occasionally, some of the following helps. But it's never the same as starting with an 8" x 10" image at 300 ppi.

    Smooth first:
    1. Upsample using FILE > FILE FORMAT PLUG-INS > IMPORT > PHOTOZOOM PRO 2. Supposedly, they are using "splines"to get interpolation from more tiles than the standard bicubic which only smooths by using 3 adjacent pixels in two dimensions. It will do very little for your example.
    2. SELECT and then GAUSSIAN BLUR areas which do not need sharpness. It makes the lines look sharper by contrast. This may help a lot if followed by sharpening.

    Sharpen
    1. The internet is filled with algorithms which claim to sharpen. They don't seem to work any better than the ones I've tried in Photopaint but look them up anyhow.
    2. The heavy hitter on sharpening is EFFECTS > SHARPEN > UNSHARP MASK. Look it up in HELP. Use it last since other techniques may wipe out its benefits.
    3. Increase contrast in both tone and color. I prefer S Curves in all three Lab curves (L ,a, b). Again, contrast will give the appearance of greater sharpness.
    4. Try out all the effects in EFFECTS > SHARPEN. Some photographers have had good luck with the MEDIAN filter.
    5. Believe it or not, adding noise may help. It may mask the pixellation which is your primary problem.

    As always, the best solution is to start with a fine grain image.

    GOOD LUCK.

    Phil
    PS: Can you post the original image as a JPEG. Use maximum quality.
    Just out of curiosity, I would like to give it a try.
  • 0 over 8 years ago

    Not enough resolution in this file. For other files there is photo-Zoom Pro that ships with CDGS. Export for and it's an option, but there are limitations.

  • 0 over 8 years ago

    32x32 dpi is a very low resolution, There's no way to make it better. If the image has good resolution you can enlarge a little (ie 120%) without losing visual quality, but if the image is small or if it's low resolution, there's nothing you can do. According with the image, sometimes you can draw as a vector, then enlarge, but if the image is not clear, it will be also difficult for draw accurately. btw the original size is also important. if the file is big size (for example, 45x30 cm), you can resample at bigger size (such as 50x35 cm) with only a little difference. Resmpling at 300 dpi will only add blur to the image, but it doesn't give real quality

  • 0 over 8 years ago

    Hi Brumble,

    If it's a drawing of a border design, you may get excellent results with the upsample, blur, sharpen technique.

    Below is a screen shot of the process.

    1. Original -- 32 x 33

    2. Upsampled to about 550 x 550

    3.  Blurred

    4.  Sharpened  (I used the L curve in the Lab mode Curves dialog.)



    Phil
    PS:  It doesn't work nearly as well with photographs.

© Corel Corporation. All rights reserved. The content herein is in the form of a personal web log ("Blog") or forum posting. As such, the views expressed in this site are those of the participants and do not necessarily reflect the views of Corel Corporation, or its affiliates and their respective officers, directors, employees and agents. Terms of Use / Privacy​ ​/ ​Cookies / Terms and Conditions / User Guidelines.