I'm just starting out with stacking in DSS and am a bit unsure about what is really happening with regard to file size. My .CR2 files are around 19Mb and 4752 x 3163 pixels. Considering the stack of ~8 images is still roughly the same pixel size, I would have thought that it is simply storing new pixel values representing the stacked values, hence the file should not be significantly larger, but the saved .tif file out of DSS is ~90Mb. It seems like the cell values aren't really merging, but being retained as a stack of separate values, hence multiplying the file size? (I realise .CR2 and .tif are different formats but I doubt they should differ by that much). Formats aside, I'm left with a 90Mb .tif which turns to absolute garbage trying to get it down to 200kb to post here. I've tried the "save to web" option that others have suggested but the quality is very poor. The closest I've got to 200kb is if I do a "print screen" and then resize the screen grab. What am I doing wrong? So many of you post images that contain such detail; even at 200kb, so I'm keen to learn how it is done.
Hi Bruce,
I can't really help with DSS as I don't use it but is it saving the TIFF with layers from the stacking? That might explain the file size.
As far as saving to JPG to upload to the forum - are you reducing the pixel dimensions of the file? I find that it is best to be at something like 1200 pixel wide at the maximum (landscape format) and of course reduced to 72dpi. If you reduce the size to that and then 'Save to Web' (Photoshop?) with a 'compression quality' of 60 you should be under 200kb without too much JPEG artefacts. It will depends on the content of the image however.
Hope this helps.
Cheers
Dave
CR2 RAW files are highly compressed (non-lossy), whereas DSS saves TIFFs as uncompressed 32-bit images... there's a huge difference between the two.
4752 x 3163 x 4 = 60 MB raw binary data, plus other overheads gets you to 90 MB.
Most people will process their images (stretching, curves, sharpening, etc) first and then save a small JPEG image (eg 1200x800) for uploading here. Possibly link to a larger version on an external website.
Thanks to both Dave's. Dave 1, I will try that approach. Dave 2, I have been doing the image manipulation in GIMP after stacking because I read that somewhere and I feel I have better control over the 3 channel levels in GIMP than in DSS (which seems hard to do fine adjustment). I will try doing all the adjustments in DSS and see how that goes.
After a bit of testing and experimenting, I found that any post processing you do in DSS adds noise to your image that you have to deal with later.
It's ok just to have a quick stretch of your image to see what you've captured, but that's it.
my 2 cents worth
I have given the suggestions a go and the result looks significantly more like my original large .tif than before, so thanks. I had done some manipulation in DSS and did a bit more in GIMP, still as a .tif. I then opened that in IrfanView and resized to 1200 x what-ever-the-ratio-made-it, with the output to 72 dpi. Then Save-To-Web, setting the output file size to 200kb and voila.
I know I have a long way to go on polar alignment and so much else but am enjoying it.
