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May 21, 2007 meeting notes:

Greetings Graphics Group,

 

Sliders For-r-r?
 

It was Adobe's turn this month as we tried out some suggestions from professional trainers of Photoshop.  A handsome HS senior boy was our subject as I had just done a shoot of him for my boss.  I picked several raw photos out of the pile and we began with Levels while referencing a Photoshop User article for improving grayscale images by Ben Willmore.  He explains the 3 usual histogram sliders to get more contrast, just like guest speaker Lee Custer taught us years ago in v6.  That is, the black slider causes dark portions of the image to go black.  Similarly, the white slider can be used to bring out white and pastels in the highlight areas.  The middle slider smoothly adjusts everything in-between.  I use it for jpeg midtones in faces mostly.  In the graph of a particular photo, the more popular shades are higher spikes and any missing shades can be deep valleys.  Levels sliders (also available in Paint Shop Pro) are great when you don't have solid blacks and whites and want more sophisticated results than using the simple contrast sliders these programs offer. 
 
But go too far with either Levels slider and you lose detail.  Holding down the Alt key while sliding can show you the blown highlights or shadows so you can adjust carefully.  Judy reported the new Photoshop CS3 does not require that Alt key.  She also says the included ACR program has more adjustments.  Just what I was hoping for as I contemplate the $200 upgrade from PSCS.
 
Ben goes on to tell us the unmarked slider at the bottom is for Minimum Highlight and Maximum Shadow for printers.  When you send your photos to a printer, the white and black limitations of the printer and paper need to be considered.  I explained an extreme example here.  At AdSack, I had to copy photos that would print with correct contrast on newsprint.  When ink hits fibrous paper, it spreads a bit, making dark grays appear black.  Lighter tones would be absorbed into the paper, washing out some details.  With "most output devices" you can use what Ben calls a "generic setting" of 3% and 95%.  To check your printer, go to DigitalMastery.com/test and read his page. I hate to be technical, but you have to convert the percentages to numbers between 0 and 255.  The 3% becomes 247 for the box above the slider and you'd type in 13 for the 95%.  Once you are happy with the output, you can use those numbers with the same printer all the time.  Our pro printers may not need any such adjusting.  We all thought, "Printer compensation slider?  We don't need no stinkin' printer compensation slider!"  Using the generic settings, our high-contrast wall-projected senior lost the solid black mass around his face.  We we now saw shadow detail in his long locks, revealing how this might actually work well... for somebody else's printer!
 
Explaining the sliders when using Levels later led to explaining most of them in the ACR program.  I made the statement that if it weren't for Adobe Camera Raw, I may have been happy with v.7.0 or even Paint Shop Pro v8 if it could work with the camera's 12-bit photos and the greater color within AdobeRGB.  Jack always said that CorelDRAW! 9.0 did everything he needed a draw program to do, making upgrades unnecessary.  Wish that were true of photo manipulation.  Then you could buy more len$e$ instead!
 
So I closed giving the Photoshop CS2 users among us some paraphrased hints I shared for using the sliders in ACR written by Bruce Fraser in Real World Camera Raw for CS2.  I have been wanting to share this for a long time and I suggest cutting this out for reference by your monitor.  Exposure affects the entire tonal range, but it is mostly a white-clipping (blown highlights) control.  I use it to bring down any right-hand spikes, then use the Brightness slider to bring up midtones without hue shifts.  As long as I don't go over 100, it won't cause white clipping.  The Shadows slider is the better black-clipping control and more dramatic than the black slider in Photoshop's Levels.  View at 100% before converting in case areas went black you can't see otherwise.  Contrast is an S-curve that will preserve the original hues.  Saturation is also a better adjustment as it too preserves original hues, but like Brightness and Contrast, can introduce clipping.  Sharpening is relatively unsophisticated and not as flexible.  Using it in preview only helps you see to set the contrast, but use the better sharpening of Photoshop.  For high ISO especially, ACR's Luminance and Color Noise Reduction are indispensible.  I enlarge to 300% to set the sliders, then use the hand cursor to slide around and compare results when I let go.  They are faster, less destructive, and more effective than other laborious methods in Photoshop.  While you work, always watch your effect on the histogram.
 
Lastly, if you are experiencing too much shadow noise in your raw photos, try adding a third to one f-stop more light during exposure.  Then use the exposure slider to darken and bring that noise under control.  This may give you better raw file results.  It works for me.
 
Next meeting is scheduled 7pm, June 18 at the Central Library.
Bruce Switalla


 


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