Artistic Filters

[Jim Clatfelter]

I do a lot of photo editing for a web forum (yahoogroup) on digital art. I tried using the artistic filters on our photos, which are mostly 800x600 pixels. The effects are very harsh. When I enlarge the photos to at least 2000 pixels wide, the effects are quite pleasing. I can reduce the size to the original.

Since the effects of the filters depend on size, I wonder what the ideal image size is. What size image were the filters designed for? 1600x1200 (2 mp) images are too small, in my opinion. Is there an optimum image size to get the best effects from the filters?

[Tom]

Hi Jim,

Could you, please, give us two links to appreciate the difference between the original and the filtered image ?
So, we will try to reproduce your process before trying to propose an appropriate answer.

Cheers.

[Jim Clatfelter]

http://www.clatfelter.net/PhotoFiltre/watercolor.html

This link will show the original followed by watercolor method one run at different image sizes. Whay all the differences?

Jim

[Antonio]

yes it's right, a lot of filters don't work nicely with big images

[Tom]

Hi Jim,

Thanks for your page with the détails of your process.
I had try the water color method one, on your original, at format 7000x7380 and i've got this, after reduce to original size: (clic on the thumbnail)



Like you can see, the effect is yet different. So we had to think about a scale problem.
I'm not expert of numeric images, but i know that the filters use some numeric models with dots matrix, and evidently : more dots are inside, more the result is smooth. For my own images i work generaly in 2272x1704

On regard your third image in 2000 wide size, you could also apply a denoiser filter. But for my taste, the original is very, very nice in state.

cheers, very glad to read you.

[Jim Clatfelter]

Thank you Tom for trying the image. The effect is best at a certain image size. It is not good if the size is too small, and it is not good if the size is too large. The original is too small. It shows up black outlines. Your size of 7000 pixels is too big. It caused a grid to appear. My conclusion is that the filters work best on an image size of at least 2000 pixels in one or both dimensions.

I agree that the original is nice. It is part of a challenge to modify the photo in an artistic way. You can see what some have done with it at http://www.pbase.com/digitalnuts/weekly_nutcracker I was trying to get a painted look.

It looks like the results of most of the filters depend on the size of the image you are editing. My 3mp camera gives dimensions of 2048x1536. I think the filters give pleasing results with that size image. At 2mp (1600x1200) the results of the filters aren't bad, but they're a little strong still. At 800x600, as used on the digitalnuts forum, the results of running the filters are way too harsh.

I'm going to test some of the other filters. I suspect that most of them give results that are dependant on the size of the image. Adjustments are independant of image size, but filters are not. I don't know the mathmatics of filter design either. It seems if the formulas went by pixels alone, the results would be the same at any size. They must be going by percentages of image size. That's why they give poor results on very small and very large images.

Anyway, image size is something I'm going to take into consideration when I use filters from now on.

[Tom]

Just to follow the subject of the size, you meet a similar situation when you apply a pattern on an image. The scale of the pattern must be convenient with the ray of the tool in use, otherwise you apply quite monochrom color.

Thank you Jim for the link to your galery, it is very interresting to look at the different ways to increase the value of a photo (which is so good at first).

I will read you again with pleasure.

[Antonio]

yes, very nice effects