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| The following are posts written to the Usenet Photoshop newsgroups. |
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| CALIBRATIONS AND SETTINGS
Making your monitor truly black:
Before setting Adobe Gamma, its best to have your monitor set to a true
black. Try the following with your room fully darkened.
Remove any wallpaper
and set the background on your computer to a pure black with no patterns.
Use your monitor controls to squeeze the desktop so you can see a black bar
across the top or bottom or both.
Turn the contrast on your monitor all the way up. Then adjust the brightness just until the black of the background matches the black edge of the blank portion of the screen. |
Set it so when
you turn up the brightness any more it no longer matches.
Now you are ready to run Adobe Gamma. You also might try turning off single view gamma so instead of the gray box you adjust the red green and blue boxes individually. Its not a huge difference though. I think once you have the monitor set to a true black before you start you will get a good result and won't feel like fiddling with the brightness when you are done. You can replace your wallpaper and patterns when you are done of course. Based on letters in this newsgroup and my own personal experience, checking the use monitor compensation box hurts more people than it helps.
-Robin |
| Calibration.
This site has it all. |
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Sorting Plugins
Not a lot of people know this, but you can choose which folder you want to
use as your plugin folder during startup of Photoshop, if you hold down
ctrl-alt when you launch the program. This will allow you
to sort your Plugins into different folders.
Holding down ctrl-alt will make two dialogs appear that will let you change
scratch disk settings, and the location of the plugin folder.
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This is also handy for those of you that have had to reinstall Photoshop because it crashed on startup, because one of it's
scratch disks had been
removed from the system (the other way to do this is to delete the settings
file).
--Jared Forrer |
MAKING GIFS TRANSPARENT
Make the background color the color of your webpage. Insert your text with Anti-aliasing on. Use Merge Down in the Layer menu. Use magic wand with 0
tolerance and anti-aliased unchecked and select the back ground color. Press
Del. Save as gif and Voila!
--Charles McEvoy |
First make sure that your text or icon is on its own layer. Then choose an obnoxiously bright colour in it's purest form, like super bright blue. Now go into Image/ Mode and select Indexed color... it will ask if you want to flatten the image and the answer is YES. Now go into File/ Export/ Gif89. Once that is done you'll be see a palette. In here you can now remove all the little boxes that have blue which basically will leave you with only the colours you want. All that's left is to save. Oh! I forgot to mention only use a background colour that doesn't appear in your text or icon, otherwise you'll end up removing the colours from it as well! Good luck! 8) |
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GIF transparency
is "all or nothing." A pixel is completely
transparent or
completely opaque, with no in-between.
When you create text in Photoshop, Photoshop will anti-alias the text--that
is,
Photoshop will put translucent pixels of intermediate value along the edges
of
the letters, in order to trick the eye into thinking the text is smoother
than
it is.
These translucent anti-aliased pixels are causing your problem. Since
GIF images must be completely transparent or completely opaque, the
translucent anti-aliased pixels do not display correctly. |
To fix this problem, you have three options:
1) Turn off anti-aliasing in the Text dialog. The edges of the letters will
not
look as smooth, but the letters will display over any background.
2) Create the text over a background color that is the same color as your
webpage
background.
3) In the Gif89a export dialog, choose a "matte color" that is the
same color
as your Web page background.
--TacitR |
Keyboard
Shortcuts
Transform
Modifier Keys:
* Shift-drag a bounding box node to do uniform deformations (i.e. to maintain aspect)
* Alt-drag bounding box nodes for proportional transformations (i.e. transform from the center)
* Ctrl-drag nodes to skew/shear the selection (i.e. perspective deformation)
* Drag the mouse inside the transform bounding box to move the selection (use the Shift key to move along 45º lines)
* Drag the mouse outside the transform bounding box to rotate the selection
(use the Shift key to rotate in 15º increments)
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Tip: Try using combinations of the above keys (e.g. the example below uses
Ctrl+Alt+Shift-drag on a node to do a proportional, uniform, perspective deformation - you might need a third hand for that one ;-).
The above info is from the TRANSFORMING A SELECTION of my
Selection Secrets
2 tutorial
--Trevor Morris |
Keyboard Shortcuts
Ctrl+Plus = Zoom In
Ctrl+Minus = Zoom Out
Ctrl+Alt+Plus = Zoom In with Resize Window
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Ctrl+Alt+Minus = Zoom Out with Resize Window
Ctrl+0 = Fit Screen
Ctrl+Alt+0 = Actual Size (Pixels)
--Trevor Morris |
| Blending Modes
These are the easier ones - Soft Light is a bit more complicated. :)
Probably the best way to visualize what the blending modes do is to make 2 layers. Make a linear horizontal black-to-white gradient as a
background, then put a linear vertical black-to-white gradient layer over it. Change the layer blending mode to see how they interact.
Soft Light and Hard Light are versions of the Overlay mode. If you understand Overlay, then just think of Soft Light as a milder version, and Hard Light as a more extreme (contrasty) version of Overlay.
Here's what I once figured out for Overlay:
For each color channel
If (Y <= 50) THEN Z = XY / 50
If (Y > 50) THEN Z = 100 - (100-X)(100-Y) / 50
Y is the Base color component, X is the Overlay color component. X,Y, and Z are percentage values. If calculating with 24-bit rgb values, substitute divisor 100 with 256. Note that a different
calculation is made depending on the value of the base color component (Y).
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The resulting pixel (z) is dependent on whether the Overlay color (x)
is greater or less than 50% black. If it?s less than 50%, Overlay acts something like Multiply mode, except that the effect is
substantially softened. (Colors are darkened by far less than what they'd be if Multiplied.) If x is greater than 50%, Overlay acts
something like Screen mode, except that the effect is substantially
softened. (Colors are lightened by far less than what they'd be if Screened.) The two formulas above produce mirrored results; i.e. 10%
X and 10% Y produce a result of 2%, 90% X and 90% Y produce a result of 98%.
If the Overlay color is 50%, the base color is not changed, making 50% gray the neutral color for Overlay mode.
For color pixels: Each color channel is calculated, separately, with its corresponding color channel for the other pixel. Each resulting color component value will follow the rules above for gray.
Therefore, because values in each color channel can be changed irrespective of each other, hue and saturation can be affected, as well as brightness.
This is how the User Guide describes Overlay:
Multiplies or screens the colors, depending on the base color. Patterns or colors overlay the existing pixels while preserving the highlights and shadows of the base color. The base color is not replaced but is mixed with the blend color to reflect the lightness or darkness of the original color.
That description works for me. You may want to check the User Guide for other descriptions.
--Ross
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Blending Modes
Normal
Edits or paints each pixel to make it the result color. This is the default mode. (Normal mode is called Threshold when you’re working with a bitmapped or indexed-color image.)
Dissolve
Edits or paints each pixel to make it the result color. However, the result color is a random replacement of the pixels with the base color or the blend color, depending on the opacity at any pixel location. This mode works best with the paintbrush or airbrush tool and a large brush.
Behind
Edits or paints only on the transparent part of a layer. This mode works only in layers with Preserve Transparency off and is analogous to painting on the back of transparent areas in a sheet of acetate.
Clear
Edits or paints each pixel and makes it transparent. This mode is available for the line tool (), the paint bucket tool (), the Fill command, and the Stroke command. You must be in a layer with Preserve Transparency off to use this mode.
Multiply
Looks at the color information in each channel and multiplies the base color by the blend color. The result color is always a darker color. Multiplying any color with black produces black. Multiplying any color with white leaves the color unchanged. When you’re painting with a color other than black or white, successive strokes with a painting tool produce progressively darker colors. The effect is similar to drawing on the image with multiple magic markers.
Screen
Looks at each channel’s color information and multiplies the inverse of the blend and base colors. The result color is always a lighter color. Screening with black leaves the color unchanged. Screening with white produces white. The effect is similar to projecting multiple photographic slides on top of each other.
Overlay
Multiplies or screens the colors, depending on the base color. Patterns or colors overlay the existing pixels while preserving the highlights and shadows of the base color. The base color is not replaced but is mixed with the blend color to reflect the lightness or darkness of the original color.
Soft Light
Darkens or lightens the colors, depending on the blend color. The effect is similar to shining a diffused spotlight on the image. If the blend color (light source) is lighter than 50% gray, the image is lightened, as if it were dodged. If the blend color is darker than 50% gray, the image is darkened, as if it were burned in. Painting with pure black or white produces a distinctly darker or lighter area but does not result in pure black or white.
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Hard Light
Multiplies or screens the colors, depending on the blend color. The effect
is similar to shining a harsh spotlight on the image. If the blend color (light
source) is lighter than 50% gray, the image is lightened, as if it were
screened. This is useful for adding highlights to an image. If the blend color
is darker than 50% gray, the image is darkened, as if it were multiplied. This
is useful for adding shadows to an image. Painting with pure black or white
results in pure black or white.
Color Dodge
Looks at the color information in each channel and brightens the base color
to reflect the blend color. Blending with black produces no change.
Color Burn
Looks at the color information in each channel and darkens the base color to
reflect the blend color. Blending with white produces no change.
Darken
Looks at the color information in each channel and selects the base or blend
color whichever is darker as the result color. Pixels lighter than the
blend color are replaced, and pixels darker than the blend color do not change.
Lighten
Looks at the color information in each channel and selects the base or blend
color whichever is lighter as the result color. Pixels darker than the
blend color are replaced, and pixels lighter than the blend color do not change.
Difference
Looks at the color information in each channel and subtracts either the
blend color from the base color or the base color from the blend color,
depending on which has the greater brightness value. Blending with white inverts
the base color values; blending with black produces no change.
Exclusion
Creates an effect similar to but lower in contrast than the Difference mode.
Blending with white inverts the base color values. Blending with black produces
no change.
Hue
Creates a result color with the luminance and saturation of the base color
and the hue of the blend color.
Saturation
Creates a result color with the luminance and hue of the base color and the
saturation of the blend color. Painting with this mode in an area with no (0)
saturation (gray) causes no change.
Color
Creates a result color with the luminance of the base color and the hue and
saturation of the blend color. This preserves the gray levels in the image and
is useful for coloring monochrome images and for tinting color images.
Luminosity
Creates a result color with the hue and saturation of the base color and the
luminance of the blend color. This mode creates an inverse effect from that of
the Color mode.
--[CMD]Wulfereene |
ERGONOMICS
I want to tell you about a work setup I would recommend to anyone who has
1) the will to better their ergonomics and speed up their workflow
(massively)
2) A lot of money to spend on their health
3) The patience for a semi-steep learning curve, and some time to adjust.
What is needed :
Datahand (www.datahand.com) (There is also a mouse built into the datahand)
Wacom Tablet (www.wacom.com - I recommend the Intuos A4 9x12)
Kinesis Programmable 3 key footswitch
Kinesis Programmable 58 key keyboard (www.kinesis-ergo.com)
Explanation :
I recommend you take a look at the Kinesis site and the datahand site to see
the devices I am talking about.
The datahand is a split-keyboard in a very untraditional sense : Left and
right hand can be separated as much as you'd like.
The footswitch and the 58 key keyboard are two input devices that can be
hardware programmed to be :
1) Any key
2) Any key combination
3) Any sequence of keys. The Wacom tablet I take for granted everyone is familiar with.
The Setup :
- The Wacom tablet is always placed right in front of me on the table, exactly where you would normally put it after moving your keyboard out of
the way.
- The datahand was ordered with a 2-foot cable between the hand units (I
recommend that you take a look at the links so you can see what I am talking
about), so one hand can be placed on each side of the Wacom tablet for
perfect keyboard operation.
- The kinesis 58 key keyboard is placed to the right of the right datahand
unit (I am left-handed).
- The 3 key footswitch is placed at my feet.
The footswitch is set up to be the ctrl, alt and shift keys.
The 58 key keyboard has it's keys programmed with various often-used, or
difficult-to-grip keyboard shortcuts, most of them for Photoshop, but also
some for painter and some programming symbols (I am also a programmer). The
keys have the symbols from the toolbar or small descriptive symbols or words
on them. |
The result :
- I never have to move ANYTHING on my table; I have perfect ergonomic and
comfortable use of all my input devices with no need to rearrange anything
for any other reason than change and increased comfort. Normally you would
move the keyboard out of the way to use your tablet properly, and move the
tablet to get to the keyboard properly. Also it is a real pain in the butt
to use multi-key keyboard shortcuts on a keyboard standing at the other end
of the tablet. Just try doing a ctrl-z without moving your left hand, if you
are left-handed.
- I use 4 limbs simultaneously for input, instead of using 1.5.
- I have all my most used Photoshop shortcuts right by my right hand for
no-nonsense single handed operation
- I have my feet controlling the shift-alt-ctrl keys, which are the most
used modifiers for the tools in all adobes programs.
Future plans :
I am looking at different voice control, and symbol control (like Sensiva)
programs that might speed up things even more, making me move my hands even
less to the 58 key keyboard.
Consider how much better it is to use a program like Sensiva with a tablet
instead of a mouse.
It takes some time to master, but the even just the option of having your
keyboard at it's ideal position AND having your Wacom tablet at it's ideal
position is unbelievably comfortable, not to mention timesaving.
The footswitch is another sweet deal, once you get used to it.
I am still learning to use this setup properly, but I can tell you already
that it's faster than the normal deal, and it has the definite potential to
make peoples jaws drop (I am talking something like a 100% speed increase
once you are good.)
--Jared Forrer
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Channels
What is a channel?
A single, precise definition is possible, but an example may lead to a
better understanding. Let's say you had a picture in Photoshop.
Photoshop calls this picture a layer. This layer is made up of a bunch
of pixels (the tiny visible pieces of the picture), say 600 across by
400 down. Let's say that you wanted to describe those pixels in some
way. It doesn't matter what the characteristic is, but it can only be
described by numerical values. You would need a 600 x 400 matrix of
values - one for each pixel. That matrix (rows and columns) of values
would be a channel.
What does a channel look like? A channel really doesn't "look" like anything, but if you take each of its values, and turn that into a shade of gray, you get a grayscale image that has the same pixel dimensions as the picture - in the case above, 600 x 400. A channel in Photoshop can have values from 0 to 255. If a value is 0, then it looks like black. If a value is 255, then it looks like white. Values in between 0 and 255 look like various shades of gray.
Channels As Selections or Masks: Whether you use the Rectangular Marquee, Magic Wand, Select>Color Range..., or any other selection tool or method, every selection is a temporary channel. For every pixel in the image, the channel has a value (0-255) that describes "how selected" that pixel is. If you go into Quick
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Mask [Q] mode, you can see and edit the temporary channel.
Quick Mask mode, by default, shows a partially transparent red overlay
(rubylithe) where areas are selected (or not selected depending on how
your options are set). You could set it to show the normal grayscale
representation if you wanted.
You can make a selection into a permanent channel in the Channels palette by clicking on the 'Save Selection As Channel' button. This channel is often called an alpha channel or mask channel. A channel can be used at any time to reload the selection.
When you create a new alpha channel (or switch to Quick Mask mode), you can paint on it, fill it, filter it, adjust it, etc. to create what can be used as a selection. Because channel values are the same as grayscale values, anything that you can do to a grayscale image can also be done to a channel. For example, painting with white is the same as selecting every pixel the paint brush passes over.
The fastest way to turn a channel into a selection is to Ctrl-click (Command-click on a Mac) the channel in the Channels palette. You'll get a selection based on the channel's grayscale values. Once you have the selection, you can select any layer in the Layers palette, and do anything to the selected pixels on that layer you want.
(continued)
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(continued)
Layer Masks:
Layer Masks are also alpha channels. Whereas regular alpha channels
are always available, and not associated with any particular layer, a
Layer Mask defines the transparency for each pixel on a single
associated layer. Make a layer that has a layer mask the current layer
and you'll see the layer mask in the Channels palette. You won't see
it when other layers are active. Regular alpha channels don't
contribute to the way an image looks, but a Layer Mask is always
actively masking a layer (unless you turn it off).
Color Channels: If you didn't know that channel values can be used to describe more than a single characteristic of pixel values, you might be confused by the fact that Photoshop uses two kinds of channels. Both types are shown in the Channels palette: The alpha (or mask) channels described above, and Color channels. Color channels store the color information for the pixels that make up its associated layer. A layer in a Grayscale mode image has one 'color' channel, called 'Black'. A layer in a Color mode image is composed of multiple color channels, one for each color component. In an RGB mode image a layer has three color channels, CMYK has four, etc.. Every layer needs its own color channel(s) to define how the pixels on that layer are colored (or shaded if grayscale).
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The color channels that define a layer determine the color of each
pixel in that layer. What color channels have in common with alpha
channels is that they are also 8-bit (0-255, grayscale)
representations of values for each pixel in the layer. Where an Alpha
channel tells you how a particular pixel will be masked (or selected),
a Color channel, say red, tells you how much red will be used for that
pixel. If you were to paint with black on the Red channel, you'd be
"erasing" the red in the corresponding pixels in that layer. If you
raised the brightness of the Blue channel, you'd be increasing the
amount of blue for every pixel in the layer (unless it was already at
maximum [255]).
Did you know that if you Ctrl-click a Color channel in the Channels palette you can turn it into a selection as if it were an alpha channel? Photoshop just uses the color component values as selection values instead.
Only Photoshop (.psd) files can save layers, and only a few file formats can save alpha channels. TIFF can save alpha channels, JPG and GIF do not.
-- Ross
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Photoshop Tips from the Newsgroups
