Roger_Cavanagh
17th of May 2002 (Fri), 10:46
I've just come back from a cruise through the Panama Canal, which was great, but the weather was not kind. Although it was bright and _very_ warm, there was strong haze the entire time. I was not optimistic about LS342 results "out of the box".
Anyway, fired up BreezeBrowser and did a linear TIFF convert all on the 300 or so shots from the actual day going through the canal; kicked off File>Automate>Batch in PS7 and went to bed. Next morning my fears proved to be justified - loadsa images like this:
http://www.rogercavanagh.com/images/autocolour/ls-hi.jpg
The histogram was very restricted:
http://www.rogercavanagh.com/images/autocolour/histogram.gif
So I was plodding through a selection of images one at a time, doing levels and curves adjustments, when I noticed a new command Image>Adjustments>Auto Color. "What does this do?", I thought. Nothing ventured, nothing gained. I clicked the button... "Ooh, this looks good!" I explored the help manual, which says:
The Auto Color command adjusts the contrast and color of an image by searching the actual image rather than the channels' histograms for shadows, midtones, and highlights. It neutralizes the midtones and clips the white and black pixels based on the values set in the Auto Correction Options dialog box.
The options dialogue looks like this:
http://www.rogercavanagh.com/images/autocolour/ac_opts.gif
After some testing, I decided to reprocess the entire batch of files using these settings. Using auto levels/contrast in PS6 would have been pointless - too many images would have been badly screwed. Not so with auto color: all the results _are_ usable. That's not to say, individual tweaking couldn't make an improvement, but it's not feasible to do that on every image.
So here's the result:
http://www.rogercavanagh.com/images/autocolour/ls-hi-ac.jpg
I cropped out the bottom third of the image to reduce the size and remove the water of Lake Gatun, which was the only thing in that part of the picture (I think it's a more pleasing image cropped). Apart from that workflow was simple LS342 HQ chooser (I picked high sharpness just for for this example), auto color, convert to Adobe RGB, downsize, convert to 8-bit, convert to sRGB, save as ProjJPEG (quality 70,20).
Images that had a broader dynamic range (wider histogram) in the first place don't exhibit much difference before and after auto color. My conclusion is that it would appear to be a worthwhile addition to include auto color in the standard LS342 workflow, but I would like to do some more testing on the best options settings.
I hope this is of some interest and help.
BTW, PS7 _is_ an expensive upgrade. Lots of reviewers have mentioned the new healing brush, which is pretty good, but the File Browser is a tremendous time-saver. With this and auto color, I'm happy that I got my money's worth.
Regards,
Anyway, fired up BreezeBrowser and did a linear TIFF convert all on the 300 or so shots from the actual day going through the canal; kicked off File>Automate>Batch in PS7 and went to bed. Next morning my fears proved to be justified - loadsa images like this:
http://www.rogercavanagh.com/images/autocolour/ls-hi.jpg
The histogram was very restricted:
http://www.rogercavanagh.com/images/autocolour/histogram.gif
So I was plodding through a selection of images one at a time, doing levels and curves adjustments, when I noticed a new command Image>Adjustments>Auto Color. "What does this do?", I thought. Nothing ventured, nothing gained. I clicked the button... "Ooh, this looks good!" I explored the help manual, which says:
The Auto Color command adjusts the contrast and color of an image by searching the actual image rather than the channels' histograms for shadows, midtones, and highlights. It neutralizes the midtones and clips the white and black pixels based on the values set in the Auto Correction Options dialog box.
The options dialogue looks like this:
http://www.rogercavanagh.com/images/autocolour/ac_opts.gif
After some testing, I decided to reprocess the entire batch of files using these settings. Using auto levels/contrast in PS6 would have been pointless - too many images would have been badly screwed. Not so with auto color: all the results _are_ usable. That's not to say, individual tweaking couldn't make an improvement, but it's not feasible to do that on every image.
So here's the result:
http://www.rogercavanagh.com/images/autocolour/ls-hi-ac.jpg
I cropped out the bottom third of the image to reduce the size and remove the water of Lake Gatun, which was the only thing in that part of the picture (I think it's a more pleasing image cropped). Apart from that workflow was simple LS342 HQ chooser (I picked high sharpness just for for this example), auto color, convert to Adobe RGB, downsize, convert to 8-bit, convert to sRGB, save as ProjJPEG (quality 70,20).
Images that had a broader dynamic range (wider histogram) in the first place don't exhibit much difference before and after auto color. My conclusion is that it would appear to be a worthwhile addition to include auto color in the standard LS342 workflow, but I would like to do some more testing on the best options settings.
I hope this is of some interest and help.
BTW, PS7 _is_ an expensive upgrade. Lots of reviewers have mentioned the new healing brush, which is pretty good, but the File Browser is a tremendous time-saver. With this and auto color, I'm happy that I got my money's worth.
Regards,