Rendering to Disc

Hi!

I am a newbie using Ultra Fractal 6.02 (64-bit).

I created a fractal 800 px (w) by 600 px (h) at 600 PPI.

When I render the fractal to disc, these are the specs:

File Format: JPG
Width: 1,600 px
Height: 1,200 px
Res: 600 PPI
Forced Linear Drawing Method: Checked

But when I opened the JPG in Corel PSP, the image was rendered at 72 PPI. Why?

Thank you!

Dr. T

I don't have Corel PSP so can't really answer this but I have two thoughts:

1. UF's Help explains that the JPG format does not support resolutions. See Help file > Resolution.

2. Perhaps Corel is set to display the image at 72 PPI, which is the typical resolution of a PC monitor.
   Can you change that??

Dear Chris,

Thank you for your reply.

I looked at Help > Resolution and it does say that "resolutions values are not supported by the JPG file format." Well, while it may be true in UF, is not a true statement. I'll try PNG.

FYI, if the file is saved from outside Corel PSP, like UF, all PSP does it to display the file attributes including the resolution.

Dr. T

Dear Chris,

This is for information purposes only.

I tried PNG and UF saves it at 200+ PPI. I tried BitMap and UF does save it at 600 PPI. Bug in UF?

Dr. T

I suspect Corel PSP was displaying your first JPG image at 72dpi because the image lacked that information - perhaps 72 is the default display mode in that situation?

I normally render all my images as .png @300dpi and do not have the problem with the resolution you describe above. I just tried a quick render at 600dpi and that resolution is what is displayed in both my image viewing program (Zoner Photo Studio) and Photoshop CS6 so I believe UF is behaving as it should.

If you want a second opinion perhaps you could do a simple render of something as a .png @ 600dpi and upload the image here or post a link to it in your cloud drive if you have one. I'll see what my program says about it... ?

Dear Chris,

The file is stored at http://www.acrylicmath.com/IMAGES/Newton 1.png

Original: 800 px by 600 px at 600 PPI
Rendered to disc: 1,600 px by 1,200 px at 600 PPI
Results: 1,600 px by 1,200 px at 236.22 PPI

Dr. T

Well, I don't know why you are seeing odd results like that, your image is reported as 600 dpi in two different programs here:

Don't worry too much about ppi, ppcm, or other "per unit" values. The important thing is the pixel dimensions of the image. If you have an image that is 1600x1200 pixels and you display it on a 22" monitor as large as possible, it will be about 14x10.5 inches (depending on the monitor), which is about 114.3 ppi. If you print the same photo at 8x6 inches, it would be 200 ppi. If you print at 12x9 inches, it would be 133.3 ppi.

In other words, ppi will change depending on the size at which it is displayed or printed. Most image editors, including Corel PSP, allow you to change the print resolution or print size without changing the pixel dimensions. This won't change the image at all (no resampling is done); it just changes some information values in the file.

With fractals, it's best to avoid changing the pixel dimensions in an image editor (resampling). If you need a different resolution, re-render with new pixel dimensions. To calculate the pixel dimensions you need, multiply the size by the ppi. For example, if you want to print a 16x9 image at 250 ppi, the pixel dimensions would be 4000x2250 (this is a different aspect ratio from the example above).

Dear Chris,

Thank you!

I also opened the file w/ another application (Paint from Windows 7 Pro) and it shows 600 PPI.

I queried a PSP Forum about it.

Dr. T

Dear rsidwell,

Thank you for your reply.

I recognize that I really don't understand PPI. To me, if a file has 1,600 px by 1,200 px, the file has 1,920,000 px in total. And, that's that. Is it not?

Now, if I send the file to a third party (e.g., Simple Canvas Print) to be printed on a 16 in. by 12 in. stretched canvas, which is 192 sq. in., what would be the resolution?

Dr. T

Dear Chris,

I got a reply from the PSP Forum. I was looking at Pixels Per Centimeter! :-(

Dr. T

Ah yes, centimeters makes sense! Well, we got the answer in the end. ;-)

I agree with rsidwell - don't worry too much about dpi, focus on the pixel size instead. So just take the size of print you want and multiply x and y inches by 300, which is typically considered very high quality by most printing companies unless you're opting for superfine giclee art prints which use microscopic ink droplets and can manage up to 1440 dpi on special papers. These probably come with eye watering price tags as well.

So your 16" x 12" print should ideally be from a 4800px x 3600px image. Bear in mind that on canvas or textured surfaces the dpi is less critical because the surface is not that smooth so you wouldn't see the super-small detail anyway.

If you want to be absolutely certain of producing the best possible file size then you really need to check with the printing firm - they should have recommended image sizes or can tell you the exact dpi capability of their equipment. Use that information to work out what you need to produce..

Dear Chris,

Mystery solved!

Usually, I print at 300 PPI but I thought trying 600 PPI for fractals.

Check what I've done at 300 PPI at www.acrylicmath.com

Dr. T

Are you the Dr. Anthony Rodriguez mentioned on that site, then? Good to meet you! I had a quick peek at your Etsy site too and have a better idea of the style of art you are interested in.

If you're a fan of Mondrian, Kandinsky etc. then you might like to explore the Barnsley type of formulas in UF. These can yield interesting blocks and shapes that are also fractal in the way they iterate. Some of the Barnsleys can be rather complex and difficult to navigate, though, but you could try Barnsley TechnoJ (UF4) (ea.ufm) or one of the Fun Barnsley (Julia) (reb.ufm) for starters.