Best way to scale down / resize images

What method are you using to resize your images in PhotoPerfect? I recently had to scale down some screenshots for a manual, and was not very happy with the results I got with the standard Photoshop resizing algorithm.
The results of the standard PhotoPerfect filter in the resize dialog (Reshape->Resize), or even better with the Lanczos3 filter, produce much better results (e.g. the edges are more rounded, the image is not as grainy and overall the quality is much closer to the original image). Are these methods generally preferrable, or is this just true for a particular type of image?

Thanks,
Al

Hi Al,

This coincides exactly with my experience. The Lanczos algorithm produces a more crisp result after resizing and is IMO superior to Bicubic or Bicubic sharpen in this respect. Besides Lanczos accepts more sharpening resulting in even more sharp end-results. The edges are however a tad rough. If you would like to have more pleasant edges, B-Spline is recommended.
Both algorithms - Lanczos and B-Spline are relatively slow though - well there is a clear reverse correlation between quality and speed ;-)

Best regards

Hoang-Tran

Speed ist my least concern, when trying to achieve optimal results...
so what about the other algorithms in PhotoPerfect like nearest neighbour, linear, Box, triangle, Mitchell or even the one called PhotoPerfect?

Which one would you recommend for which purpose?

Cheers,
PhotoWebber

Hi Photowebber,

If quality is your main concern, then Lanczos, PhotoPerfect or B-Spline are your best choice. They offer the best quality and suitable for both downsizing and upsizing. Personally I like Lanczos most, but in some case the results might be a tad too rough. B-Spline and PhotoPerfect create slightly smoother results. Mitchell is still good at upsizing. The rest is fast but visibly inferior.

Hope this helps a bit

Hoang-Tran

Hi Hoang-Tran,

regarding upsizing / increasing image size: if I want to work with only one method, I understand from your message that Lanczos is still the method of choice for upsizing / increasing image size? (if interested more in quality than in speed)

Regards
-Al

Hi Al,

Either Lanczos or B-Spline + a tad sharpening (e.g. USM or 3D sharpness...) would serve you well. Depending on your taste you could not be wrong choosing one of these 2 methods IMO.

Best regards

Hoang-Tran

Hi,

Due to some users' request, I have just tested Lanczos vs. BSpline extensively for upsizing.

-If your original photos' quality are real good, then Lanczos maybe the more suitable algorithm.

-Otherwise I would choose BSpline for less optimal photos, as Lanczos may be too strong in sharpening and thus might generate undesirable artefacts. BSpline on contrary is more gentle, leaving the sharpening to you. This is good as you have total control over this parameter. By combine sharpening amount and methods, you can avoid artefacts then.

Best regards

Hoang-Tran