What is Sigma Pro software doing when saving image as "double size."?

Does double size JPEG file saving have any negative effect on the image? I I also noticed that when I open these images in Adobe that they are saved by the Sigma pro software at a default 180 pixels/inch. When should these files be converted to 300 pixels/inch? Thanks.

There's no negative effect on the image when saving from SPP as it's doing a resize the same as you would get using other software (although I don't know what the resampling method is...chances are it's bicubic as that is the most popular). Depending on how the resampling is done, it could even be more accurate in SPP than resizing the output TIFF or JPEG file as all RAW information would be available at the time of processing to SPP, whereas that would not be the case when using PS or another program to resize.

Also, if you are using the output file as an input for additional processing, you should use TIFF as that will not have any degradation of the image as occurs with JPEG (a lossy compression method). If the output is going to a website or into an email, JPEG would be fine.

As far as changing the dpi, I do that when I output the final finished TIFF file that I intend to print.

dehlers said:

Does double size JPEG file saving have any negative effect on the
image? I I also noticed that when I open these images in Adobe
that they are saved by the Sigma pro software at a default 180
pixels/inch. When should these files be converted to 300
pixels/inch? Thanks.

Click to expand...

--
John P. Sabo
[email protected]

'Any sufficiently advanced technology is indistinguishable from magic.'

• Arthur C. Clarke -

dehlers said:

Does double size JPEG file saving have any negative effect on the
image? I I also noticed that when I open these images in Adobe
that they are saved by the Sigma pro software at a default 180
pixels/inch. When should these files be converted to 300
pixels/inch? Thanks.

Click to expand...

SPP uses simple linear interpolation to quad-size (don't know why it's called double size), as opposed to Bayer interpolation which uses exhaustive adaptive interpolation routines to do the same.

Output single size then interpolate using Genuine Fractals instead. Better still would be a Foveon specific adaptive interpolator built into SPP.

heybabyhey said:

dehlers said:

Does double size JPEG file saving have any negative effect on the
image? I I also noticed that when I open these images in Adobe
that they are saved by the Sigma pro software at a default 180
pixels/inch. When should these files be converted to 300
pixels/inch? Thanks.

Click to expand...

SPP uses simple linear interpolation to quad-size (don't know why
it's called double size), as opposed to Bayer interpolation which
uses exhaustive adaptive interpolation routines to do the same.

Output single size then interpolate using Genuine Fractals instead.

Click to expand...

From some tests, it appears that GF is about the same as other resampling methods, but since GF is a program or plug-in, it's another purchase.

http://www.americaswonderlands.com/digital_photo_interpolation.htm

http://audio.rightmark.org/lukin/graphics/lhouse_more.htm

heybabyhey said:

Better still would be a Foveon specific adaptive interpolator built
into SPP.

Click to expand...

--
John P. Sabo
[email protected]

'Any sufficiently advanced technology is indistinguishable from magic.'

• Arthur C. Clarke -

Although GF and Qimage do a great job in very specific instances, Photoshop's bicubic performed best in broad terms in our experience.

--
Laurence

There is a tide in the affairs of men,
Which, taken at the flood, leads on to fortune;
Omitted, all the voyage of their life
Is bound in shallows and in miseries.

http://www.pbase.com/lmatson/root
http://www.pbase.com/sigmasd9/root
http://www.pbase.com/cameras/sigma/sd10
http://www.pbase.com/cameras/sigma/sd9
http://www.beachbriss.com (eternal test site)

dehlers said:

I I also noticed that when I open these images in Adobe
that they are saved by the Sigma pro software at a default 180
pixels/inch.

Click to expand...

Don't worry too much about the DPI setting in the file. It really has no meaning for digital cameras which produce images of a specific size in pixels. Most cameras set it to 180 or 72 d.p.i. purely as it has to be set to something.

This setting is really intended for scanners that may be required to reproduce copies of original documents at their original size, In order to do this you need to know the size of each pixel as well as the number of pixels.

With your photographic images, when you want to print, simply resize the image to the physical size you want (e.g. 18" x 12") at a suitable DPI setting for your printer. This will normally be 300 d.p.i. for Canon or HP printers, or 360 d.p.i for Epson. Some other printers need odd settings, for example, certain dye-sublimation printers need 306 d.p.i.

Incidentally, calling the setting d.p.i. is not strictly correct. It should be p.p.i. (pixels per inch) as ink-jet printers actually use a much higher number of dots to reproduce all the different colours.

--
Thanks,
Gary.