Photoshop Tips

Adobe Photoshop is one of the most common applications that people use to edit photos, but a lot of people are overwhelmed by the complexity of the application and only use a small portion of its potential. I'd like to change that! Here are some concepts and tips that I use frequently. Paragraphs with actual "How-To" Steps from Photoshop menus are marked with ** while the other paragraphs discuss ideas that lead into those sections.

Changing Image Resolution**

Recommended Books

Optimizing Photoshop**

Print vs Screen Resolution

Depending on how you intend to display your image, you will need different resolutions. If printing your image, then the resolution I recommend will depend on your printer and its algorithm to interpolate between pixels in your saved image. In general, I print images at 350 dpi (dots per inch), but for more average printers, you should consider increasing that to 450 dpi, or even 600 dpi. The number of megapixels that your camera captures will affect how easily you can increase your image to the desired size without sacrificing quality.

If uploading your image to a website, for display on a CRT computer monitor, then all you need is 96 dpi. If you're using an LCD monitor, you may need a higher resolution for a crisp image, but that will depend on your monitor's resolution. Aim for 150 dpi and increase subsequently if that is not high enough. Bottom line: when displaying your image on the screen, you want to keep the size of the image file low so that display is quick, and you don't need the same quality resolution as for printed photos.

Changing Image Resolution

1) In Photoshop, open the image whose resolution you want to change
2) From the Image menu, select Image size
3a) To fix your image size when changing the resolution, enable the Resample Image check box
     WARNING => if you are increasing your resolution, enabling this setting will decrease image quality
3b) To fix your pixel count, disable the Resample Image check box
     WARNING => your image size will increase or decrease with your resolution change
4) Change your Resolution setting (I typically use pixels/inch - a.k.a. dots per inch) and click OK to apply
5) If you chose to apply step 3b then you can stop here. If you chose to apply step 3a then you should also apply a small amount of Unsharp Mask to sharpen your image. Continue on with step 6.
6) From the Filter menu, select Sharpen, and Unsharp Mask...
7) Change the Radius to 3 and the Threshold to 6, and scroll the Amount pointer along the bar until desired sharpness is reached.

Enlarging Images

When using Adobe Photoshop, the alorigthm used to increase image size is better if restricted to 10% per run. For example, if you need to increase an image's size by 50%, you will get a better final result if you increase the images size 10% at a time. Some advocates create a job in Photoshop and assign a special keystroke to it so as to quickly repeat the "increase to 110% of original size" action.

Saving an Action to a Keystroke

In the following example, we'll save the Action of increasing image size by 10%, but you can apply it to anything!

1) Open an image in Photoshop
2) From the Window menu, select Actions
3) At the bottom of the palette that pops open, click the Create New Action button
4) Name your Action something like "Increase image size by 10%", and choose a Function Key to save this Action against (e.g. I used F9)
5) Click the Record button
6) From the Image menu, select Image Size
7) Enable the "Resample Image" check box and set it to "Bicubic Smoother"
8) Change the Document Size Width to "110" and set the unit type to "percent" and click OK
9) Now that your Action is done, click the square Stop button at the bottom of the Actions palette to complete your recording process
10) Test out your saved Action by pressing the F-key you chose in step 4 - Voilà!

Layers

What are layers? Layers in Photoshop act the same way a stack of transparencies would act: the top layer is most visible, but you can see the layers below wherever the layer above was transparent. With Photoshop, you can do all sorts of things to layers to blend them together in different ways: you can set the opacity to less than 100%, so as to only partially view the layer, or you can blend by darkening or lightening, etc. Layers allow you to copy existing layers (or your background) or parts thereof.

TIP: It is good practice to duplicate your background into a new layer and then edit that new layer; that way, should you make a mistake, your original is always intact.

Optimizing Photoshop

Photoshop can sometimes be slow, especially when working with large images. That can be partly due to a slow computer - either processor or disk, or not enough memory. Here are some ways to change the settings on your computer and within Photoshop to optimize its processing time.

1) Configure Photoshop to use Virtual Memory, a.k.a. a scratch disk; here's how:
     a) If you have multiple disks or partitions on your computer, determine which one has the most free space outside the main C: drive
     b) From the Edit menu in Photoshop, select Preferences => Plug-Ins & Scratch Disks
     c) Select the disk that has the most free space available (only select the C: drive if you have no other disks)
     d) Optionally select secondary disks to be used, should the first disk fill up
     e) Consider changing the Image Cache setting - a number closer to 8 will speed up image redraw time while slowing time to open images; a number closer to 1 will speed up image opening, but will cause image redraw to be slow

2) Configure Photoshop to use a medium percentage of your computer's RAM; making the percentage RAM too high will result in page swapping, which actually slows down processing time
     a) From the Edit menu in Photoshop, select Preferences => Memory & Image Cache
     b) Set the Memory Usage to 50-60 % for computers with up to 2GB RAM, and 70% for computers with more
     c) Restart Photoshop to apply any changes made to Memory Usage

3) Defragment your hard drives to speed up opening and saving of files in Photoshop
     a) For Windows users, select from the Start menu your program sub-menu, then Accessories => System Tools => Disk Defragmenter and follow instructions to defrag each hard disk
     b) For Mac users, defragmentation is likely automatic, but check you user's manual for details

4) Configure Photoshop to reduce the number of actions saved in the History palette; by default it is set to 20, and each one slows down Photoshop
     a) From the Edit menu in Photoshop, select Preferences => General
     b) Reduce the number of history states from 20 (default) to the maximum number you think you'd use

5) Close other open programs, such as iTunes, Outlook, or graphically intensive applications to free up resources

For More Information...

If you're interested in purchasing only one book as reference, then I highly recommend the PhotoShop CS book by Scott Kelby (editor of Photoshop User Magazine). I use it as reference frequently while editing photos and trying to correct for mistakes I made during my latest photo-shoot.

He gears his reference material toward amateur photographers who don't care to know the detailed ins-and-outs of PhotoShop CS, but who instead want to know how to correct common problems with digital images. For example, he covers cropping and resizing tricks, corrections to common image problems (over-exposure, under-exposure, bad mix of colours, etc), masking techniques, fixing photos of people to look more flattering, and much more. I even learned to straighten a building that suffered from fish-eye distortion!

I've added a link to Scott Kelby's book on amazon.ca, which is where I purchased my copy, since it has the best price anywhere - either locally or online. It's about $40 Cdn, and ships within a day or two, but the shipping is free!

If you're more interested in advanced lighting correction for photos, or the more creative aspect of adding lighting effects to an image, then I recommend this book by Barry Huggins, which I also own. It's about the same price as the book above, but is less commonly stocked - amazon currently ships within 4-6 weeks. It covers topics such as quality of light, creating weather effects, shadows, reflections, etc. It takes your photos that extra step further.

For example, if you wanted to correct a blown-out sky, or add lightning to a stormy atmosphere, this book covers it. If you want to add beams of light through smoke or steam, this book covers it. Or, if you want to turn a beautiful image into something you'd see through a bead of glass, then the refraction and glass topic will take you through it. Through the (surprisingly easy) magic of PhotoShop's layers, you can turn your poorly lit images into something much more exciting.