DeadHeartStudio

Color space

A simple set of numbers, in either RGB or Good color management starts with a color profile, a cross-platform file that describes CMYK, does not provide enough information a particular device’s color characteristics. When a printer, scanner, or digital camera to define and reproduce exact color on is connected to your system, ColorSync automatically assigns an ICC profile to that different devices. For example, an RGB value device. In most cases, this is a profile that the device’s manufacturer has supplied—a of R10, G100, B10 does not define how that color should appear; it is just the ratio of the factory profile. While many devices come with ICC profiles that ColorSync can automatically assign, By specifying a scale for these RGB values others will need you to specify the ICC profile. Some manufacturers provide ICC within the range of human vision, R10, G100, profiles on their websites, and service providers often supply ICC profiles particular B10 can replicate how this green should to their devices. Professional users may want to create their own, as the accuracy of appear. This scale is called a color space.

Quartz is the PDF-based graphics system in Mac OS X that draws graphic elements on displays and output devices. Quartz Filters give users the ability to apply color management, effects, and other processes when creating a PDF file or printing. You can create your own Quartz Filters using the controls in the Filters pane in ColorSync Utility. More information about Quartz Filters is included in the “Using Quartz Filters” section.

Using the Calculator tool in ColorSync Utility, you can compare the impac t of color models, color spaces, rendering intents, and the translations that occur when color transformations are performed by the CMM. This tool provides a way to empirically see the impact that each element has in color transformations.

Image processing tasks like embedding color profiles can be performed easily with Automator. For example, to create a workflow that changes the color profile for a series of images, select Preview in the Automator Library and drag the “Apply ColorSync Profile to Images” action into the workflow area. You will be asked if you want to add a Copy Finder Items action so the original files are not permanently altered; if you want to apply actions on a copy of the original file, click Add. In the Copy Finder Items pane, choose any folder you wish or use the default (Desktop). In the “Apply ColorSync Profile to Images” ac tion, select an ICC profile from the pop-up
menu to use for the color conversion. This workflow can now be saved as an application. However, the real power comes into play if you save a group of actions as a plug-in. You can select different types of plug-ins depending on how you want to utilize them.

Automator plug-ins include:

Finder.

Adds the Automator workflow to the contextual menu accessible in the Finder.

Folder Actions.

Allow you to select a folder on your hard drive that will run the Automator workflow when items are added.

iCal Alarm.

Runs the workflow at times and dates specified in iCal, the easy-to-use calendaring application in Mac OS X.

Image Capture.

Runs the workflow using the Automated Tasks option in Image Capture.

Print Workflow.

Integrates your Automator workflow into the PDF Services of the Print dialog in Mac OS X, giving you access to PDF-based workflows from most applications.

Script Menu.

If you have enabled the AppleScript Script Menu, your workflow will also be accessible from the AppleScript menu in all applications. Creating an Automator workflow for assigning color profiles to images.

PDF documents in Mac OS X Tiger can be further refined using Quartz Filters. These filters let you apply color management, color effects, and other processing options such as compression or creation of files in PDF/X-3 format. To access Quartz Filters, click Filters in the toolbar of ColorSync Utility. Here you see the Quartz Filters that ship with Mac OS X Tiger. You can duplicate and modify these filters or create your own using ColorSync Utility. To create your own Quartz Filter, click the Add (+) button in the bottom left of the window and enter a name for the Quartz Filter. Press the Enter key and ColorSync Utility saves the name of your Quartz Filter. Click the triangle to the right of the name to see the Quartz Filter options. You can assign ICC profiles; convert to a new color space using profiles; apply color effects; change the bit depth, dimensions, and compression; or add comments to a PDF document. Your Quartz Filter can now be accessed from the Mac OS X Print dialog. Quartz Filters can also be accessed in Automator

Once your display is calibrated and profiled and all of your images have color profiles embedded, your Mac OS X applications such as Preview, Mail, Safari, and Adobe Photoshop are capable of accurate color soft proofing. In addition, the correct color space conversions for output are now easy to accomplish. When displays are calibrated and profiled correctly, you can share documents with colleagues using Mac OS X and be assured that they will see the same colors. For example, you can post images on your web page and those viewing them will see the correct colors in Safari. You can email files in Mail with accurate color. Applications that use Quartz are automatically color-managed using ColorSync for accurate color soft proofing.

For maximum accuracy in calibrating and Once you have captured your images and embedded the appropriate ICC color profile, profiling a display or output device, a you are ready to begin editing them to suit your needs. However, because your display hardware calibration device such as a color is the window into everything you do, first ensure that an accurate color profile is proimeter or a spectrophotometer can be used. Colorimeters are most often used for calibrating for your display. By calibrating your display and using a custom profile, you caning displays. Spectrophotometer are used trust the color you see on your display and be able to view and modify color in your to calibrate and profile displays, and they are images more accurately. It also useful for creating profiles for output While Mac OS X has already assigned a factory profile to your display, conducting your devices such as printers. own calibration of the display based on your environmental conditions is highly recommended. Mac OS X provides the tools to do this using the Display Calibrator Assistant devices, visit the Macintosh Products Guide The Display Calibrator Assistant is accessed from the Displays pane of System at www.apple.com/guide. In the Color pane of the Displays preference pane are options for selecting the current ICC color profile for your display, as well as a Calibrate button, which opens the Display Calibrator Assistant.

Creating graphics for the web

At times you may want to convert your Some color-aware applications will ask you to choose a preferred working space. A images to another color space for optimal good working space for images provides consistency in defining neutral colors. When viewing on the web. For instance, suppose all three colors (red, green, and blue) have the same value, such as R100, G100, B100, you have a number of files in Adobe and the resulting color is neutral, without any color cast or tint, the color space is con-RGB (1998), which is ideal for editing and sidered linear. Common linear color spaces like Adobe RGB (1998) are ideal for editing archiving images, but you want to post them to a web page where sRGB is a more and archiving images, while the smaller sRGB space provides a linear color space when appropriate color space. If you convert your dealing with multiple devices in a non-color managed workflow. This is not always the images to sRBG and attach the sRBG profile, case with the color profiles of RGB devices, especially those used for printing. For edit colors will be interpreted correctly by coloring and archiving, it’s best to select a working space with a gamut that overreaches or savvy applications like Safari, and the images matches the gamut of the capture (input) device. It will maintain a small gamut for adequate display on non-color-managed devices and applications.

Images need an ICC profile to define their color space. The Image Capture application lets you set your preferences for capturing and embedding these profiles in the images. The images captured are automatically color-managed. The Image Capture framework in Mac OS X allows other applications to download color-managed images as well. Image Capture automatically recognizes devices such as scanners and digital cameras and completes a number of color management tasks. You can set Image Capture to assign and embed an ICC profile in each file as images are downloaded to your Mac. This application can save you hours of work by automatically applying the correct ICC profile to each input device. As a framework built into Mac OS X, Image Capture provides a common method for downloading images from a camera and into an application. It is used by applications such as Aperture and iPhoto and by many third-party developers. With such a framework in Mac OS X, users experience a familiar method for downloading images, and developers can spend more time creating compelling applications.

SSH provides the most secure options for sharing files, but is not always convenient for many users, however, it is possible to use SSH to create an encrypted tunnel which can be used by more familiar sharing protocols such as AFP. The file sharing services enabled should largely be dictated by the location of the Mac OS X system on the network and the sensitivity of the data transferred. As a general rule, only encrypted transfer mechanisms such as SSH and VPNs should be used over untrusted networks. Unencrypted file sharing protocols such as FTP, Microsoft’s SMB, NFS and Apple’s AFP should only be used on trusted networks. When unencrypted file sharing protocols are used, the authentication credentials of users’ can be compromised by network sniffing. This is an added problem when the same credentials are used for remote system access. SSH provides a secure method for transferring files across un-trusted networks and also allows the creation of VPN tunnels between an SSH server and client. Apple has used this in Mac OS X Server(>10.2) to allow users to tunnel AFP over SSH by enabling “secure connections” on the server. Even without Mac OS X Server, it is still possible to manually create a tunnel for AFP over SSH.

From the client’s command line enter:
ssh
username@remote.server
–L 10548:127.0.0.1:548

This tells the SSH client, to connect to the SSH server and map the local port 10548 to the remote port 548. This means that all connections to the local system on port 10548 will be encrypted and forwarded to the remote host on port 548 (The port used by AFP).