TIL No:4
TECHNICAL INFORMATION LEAFLET: Printer Friendly Version (You can print directly from this webpage)
Updated: Sunday 16 July, 2006 0:46
UPSIZING IMAGES FOR PRINTING
Following a query on the dpreview.com Sigma Forum about the best way to resize (upwards) images for making larger prints, I did some research (which actually only reinforced what I have previously found several years ago) so that I could be more specific in terms of helping the person who posed the question.
Other Sigma Forum members also posted replies but I thought I would spend a little time actually checking.
Here is my reply, together with just one of the images, which for web space has to be the JPEG (TIFF not available on my web pages), originally saved from SPP at Same Size (as shown via TEXT in image), JPEG Level 12 exactly as per X3F image (no processing in SPP) then UP-sized in PhotoShop to my normal printing size, 12.5" x 18.75" and changed to 360ppi, with Bicubic selected.
The image shown is a 6"x4" section (from the resized Same-Size JPEG @ Level 12), which on my 17" monitor (when viewed on the web) is around 14" wide, so in reality, represents what would (approx.) be seen as a print of size 43" wide. No sharpening added at any time, although for printing, would probably select to use Unsharp Mask of "Amount" about 100-150% and "Radius" around 0.5 to 0.8 pixels with "Threshold" left at 0. This JPEG image section was saved at Level 8.
Also, no processing either in PhotoShop for this sample. Whilst one might normally tweak for printing, I have not changed anything for these tests, other than resizing/sampling as described.
MY REPLY (Posted 15/07/2006):
I have just spent an enjoyable couple of hours really investigating different image files - meaning different processing of the same image.
I made several saves via SPP of the same X3F file in different formats (Same and Double Sizes and JPEG level 12 and TIFF 8-bit), with most at straight X3F image file quality plus some using AUTO and AUTO slightly customised. These were all, in PhotoShop, resized to 12.5" narrow side x 18.75" longer side (with all to 360ppi, resampled via Bicubic) which would be my normal printing size. I also printed out a small section of each to compare not just onscreen but also "in the flesh".
To shorten things, lets just say I dispensed (after deciding they were just not good enough) with virtually all images on AUTO setting. One (with tweaking) made it to the end, as described below.
In basic terms, I was curious, after doing this some years ago, to see what actually happened via different processing options.
The ones that made it through to the end as being the best were:
1 x Original X3F file saved as 8bit TIFF at Same Size
1 x Original X3F file saved as 8bit TIFF at Double Size
1 x Auto processed in SPP and saved as 8bit TIFF at Double Size, with Fill Light reset to Zero and Sharpening set to -5 (as suggested some time back by Laurence)
PLUS
1 x Original X3F file saved as Same Size JPEG, Level 12
I would mention that I do little processing in SPP due using camera on Manual, except for an occasional very slight tweak should I feel it would be beneficial.To be honest, there was little difference between the lot. The part-auto (No Fill Light and -.5 Sharpening) was quite smooth but definitely would need some Unsharp Mask to make sense in a print.
Most interestingly, the Same-Size JPEG upsized was a match for both of the best (non-auto) TIFFs.
The Double-Size TIFF downsized and the Same-Size TIFF upsized were virtually the same. Possibly, if a larger print was required it might be of a slight advantage to start with the double-size 8-bit TIFF - but in all honesty, I would still expect to see very little difference. I suppose, also to be extremely honest, the Same-Size JPEG would probably be just as good too, when upsized, from what I have found on numerous testing occasions over the years!
Of interest, the resized TIFF files (via Windoze Explorer) were 89,000 as against the JPEG's only 2,974 as stored on the hard drive, which spells an enormous advantage when looking at storage space of course. For a long time, I have, after processing, always saved my finished files ready for printing in JPEG at Level 8 and have found no disadvantage whatsoever (even when on occasions, after making a test print section, I have made some small adjustments and re-saved at same level). Such files open in PhotoShop at the same size as a TIFF version, yet on the hard drive (CD/DVD) take about a thirtieth (1/30th) of the space.
This first image is just to show the total image from which the section was taken:-
The mono version below has had Unsharp Mask added - Amount 120, Radius 0.6 and Threshold 0
© - BRIAN SL ALLEN - 2006 - ©