Have Geek Brain

How do I scale the JPEG image down to make the text as clear as possible?

I have some JPEG images that I need to reduce to about 80% of their original size. The size of the original image is about 700 pixels × 1000 pixels. The images contain some computer generated text and possibly some graphics (similar to what you find in corporate word processing documents).

How do I scale the image so that the text is as legible as possible? We are currently scaling imaeg using bicubic interpolation, but this makes the text blurry and hazy.

+2


a source to share


3 answers


Two options:



  • Use a different oversampling algorithm. Lanczos gives you a much less rough result.

  • You are using an advanced JPEG library that converts 8x8 blocks to 6x6 pixels.

+2


a source


If you are not exactly 80% tuned you can try to get and build the djpeg from http://www.ijg.org/ as it can decompress your jpeg to 6/8 (75%) or 7/8 (87, 5%), and the quality of the text will be pretty good:

Original

7/8



3/4

(SO decided to scale the images when showing them)

There might be a scaling algorithm that works in a similar way, but this is a very simple shelf solution.

+2


a source


There is always a loss associated with downsizing, but that again depends on your trade-offs.

  • Blur generation and artifact generation is normal for jpeg images, so it is recommended that you generate images at the correct size the first time.
  • Lanczos is a great solution, but you have your compromises
  • If it is only text and you are concerned about it, you can try the dilatation filter on the overselected image. This will fix some of the blurriness, but may also affect the graphics. If you can live with him, that's good. Alternatively, if you can define regions of text, you can only apply the expansion to those regions.
+1


a source






More articles:


All Articles