Best resolution for original

[Mike Klein]

I'm trying to pick the best resolution to use for the original image.

Say I'm after a finished piece of 30x20in at a resolution of 300dpi what would you make the original image. I feel it can make quite a difference.

[liveart]

Mike,

By original I will presume you mean initial canvas size and not source size. I tend to like to work small to medium (640x480 small and 1280 x720 med) to start and very often include scaling up operations as part of the process. my finished piece exiting SA might be in the area of 2000x 3000 pixels. SA has a unique scaling algorithm called the supersizer. As with all scaling operations it creates certain process related artifacts or structures. In the case of the Supersizer it is specifically designed to create a more artistic look as the image is scaled up (n.b. SA also can do bicubic and noninterpolated scaling).

The decision you are making very much depends on the source image and the process that you want to apply. While the paint presets can be scaled to attempt to match a larger canvas the look will in many if not most cases be quite different from canvas size to canvas size. Which is to say that there is no set answer to your question. It really is a matter of artistic taste/vision.

As for the more technical side of your question to print a good quality image at 300 dpi in 30x20in one would need at least 4500 x 3000 pixels in the file to be printed (9000 x 6000 being the 1:1 equivalent- yes I know dpi is not the same as ppi but that would be getting way too technical). Consider that scaling up after doing your SA processing is also possible and maybe be even preferable. I like Perfect Resize from On One Software for this task. (they bought Genuine Fractals)

I have printed SA generated work as large as 65 x80 inches

[Mike Klein]

No, it was more related to source size. Most of my images have been shot on a Canon 1DS Mk3 but I'm finding I get better results if I downsize the images as a starting point. I just wondered if there was a general rule for the most appropriate relationship between source and SA canvas size. I use Alien BlowUp if I need a resize later but that would be after the SA generated image. Thanks for your thought however

[Synthetik]

It really depends on what you are doing. For painting, you can often get away with much smaller source images, since the painting process itself is adding additional detail through the textures and edges associated with individual brush strokes.

If you are using image operation effects to process a source image, then the resolution of the source image may be more important. But again, it depends on what kind of image operation effects you are working with.

If you are using the vectorizer, you may be better off working with a smaller source image. You can output your vectorizer output as a vector eps file, and then render it (as a photoshop import for example) at whatever arbitrary final print resolution you want.

So you should really experiment to figure out what works for you, the visual characteristics of the source images you are working with, and the particular digital artistic painting or visual effect approach you are following.

[Mike Klein]

Thanks. I generally dont use vectorising and have found downsizing my images produces  better results and I wondered if there was a general rule for the source/canvas relationship that works best. I'm happy to suck it and see but hoped I might short cut that.

[liveart]

You are correct that upto a point SA works better with a smaller source- sorry I misunderstood your question

actually there is a pretty easy way to figure the minimum size source you want to use for the project at hand:

set the default scaling to supersizer.  Select the canvas size you want to work with. Now try a ridiculously small source image 100 x180 pixels or some such thing...

simply drag that image on to the canvas.  you will see the "distortion" caused by the scaling. upsize your source until you do not see any "undesirable" distortion when you drag the source to the canvas (or erase to source). If you do this a few times keeping track of the source to target ratio you should have your rule of thumb pretty quickly.

I have never been quite so scientific about it, but my starting canvas sizes (640 or 1280) are also about the upper limit of where I would be sizing the source. Again it is going to be a bit of a personal taste issue but I have found that the source can be as small as 1/3 of the canvas size without much problem though I might try to keep it to a 1:1 or 1:2 ratio for most cases. (remember my initial canvases are much smaller than what your Canon is producing- so that a 1:1 source to canvas ratio would still require downsizing the original for