Photoshop
Of course, I can’t forget the native Photoshop format (.psd). This format offers a lot of benefits. First of all, along with TIFF and PDF, Photoshop allows you to save layers in your image. The other formats flatten the layers into a single background. This format works well if you are going to spend a considerable length of time working on your image. The Photoshop format also supports all image modes, is the fastest format for opening and saving, and offers all the various save options.
Like TIFF, the Photoshop format uses a lossless compression process, although it’s invisible to you. If you need to open a file in an older version of Photoshop, be sure to save it as a native Photoshop file. Finally, almost all drawing and layout programs now support the importing of Photoshop files.
Photoshop Raw
This format is designed to transfer images among applications and platforms. The Photoshop Raw format can be useful if you want to transfer an image to or from a mainframe computer or other type of device that doesn’t support the standard graphic formats. Don’t confuse it with the Camera Raw format described later in this chapter. The Photoshop Raw format supports CMYK, RGB, and Grayscale images with alpha channels. It also supports Multichannel and Lab Color images without alpha channels. The format allows for any pixel or file size, but it doesn’t support layers.
You may never have to save a file in the Photoshop Raw format. And you may not want to after you read the options involved in saving in this format. The Photoshop Raw format imports and exports files in an uncompressed, binary format. The format does not specify image size, color mode, or bit depth. It is simply comprised of bytes that represent the color information in the image. Each pixel is represented by a brightness value, with 0 being black and 255 being white. The format then includes the total number of color channels in the image, plus any other channels, such as alpha channels. In order to save a file in the Photoshop Raw format you must specify certain settings found in the Photoshop Raw Options dialog box:
-->File Type (Mac OS only): This four-character ID identifies the file type. PRAW is the default ID for the Photoshop Raw format. Leave this default setting.
-->File Creator (Mac OS only): Another four-character ID which tells the operating system which application created the file. Leave the default setting of 8BIM (Photoshop’s code), unless you know the special file creator ID for the application you plan on using the file with. Many Mac applications have file creator IDs registered with the Apple Computer Developer Services group.
-->Header: This parameter specifies how many bytes of information appear in the file before the image data starts. The default setting of 0 means there is no header. If, for example, you enter a 2, two zeros are entered at the beginning of the file as placeholders. When you open the Photoshop Raw format, you can then replace those placeholders with a header. I recommend leaving the value at 0.
-->Save Channels In: Choose between Interleaved Order and Non-Interleaved Order. The default setting of Interleaved Order stores the color data sequentially by pixels. In other words, in an RGB image, the first byte is red for the first pixel, the second byte is green for the second pixel, the third byte is blue for the third pixel. Non-Interleaved Order stores the color data by channel. In this case, the first byte is red for the first pixel, the second byte is also red for the second pixel. Once the red channel is complete, it then goes and saves the green and then the blue channel.
Your choice depends on requirements of the application that will open the file.
Of course, I can’t forget the native Photoshop format (.psd). This format offers a lot of benefits. First of all, along with TIFF and PDF, Photoshop allows you to save layers in your image. The other formats flatten the layers into a single background. This format works well if you are going to spend a considerable length of time working on your image. The Photoshop format also supports all image modes, is the fastest format for opening and saving, and offers all the various save options.
Like TIFF, the Photoshop format uses a lossless compression process, although it’s invisible to you. If you need to open a file in an older version of Photoshop, be sure to save it as a native Photoshop file. Finally, almost all drawing and layout programs now support the importing of Photoshop files.
Photoshop Raw
This format is designed to transfer images among applications and platforms. The Photoshop Raw format can be useful if you want to transfer an image to or from a mainframe computer or other type of device that doesn’t support the standard graphic formats. Don’t confuse it with the Camera Raw format described later in this chapter. The Photoshop Raw format supports CMYK, RGB, and Grayscale images with alpha channels. It also supports Multichannel and Lab Color images without alpha channels. The format allows for any pixel or file size, but it doesn’t support layers.
You may never have to save a file in the Photoshop Raw format. And you may not want to after you read the options involved in saving in this format. The Photoshop Raw format imports and exports files in an uncompressed, binary format. The format does not specify image size, color mode, or bit depth. It is simply comprised of bytes that represent the color information in the image. Each pixel is represented by a brightness value, with 0 being black and 255 being white. The format then includes the total number of color channels in the image, plus any other channels, such as alpha channels. In order to save a file in the Photoshop Raw format you must specify certain settings found in the Photoshop Raw Options dialog box:
-->File Type (Mac OS only): This four-character ID identifies the file type. PRAW is the default ID for the Photoshop Raw format. Leave this default setting.
-->File Creator (Mac OS only): Another four-character ID which tells the operating system which application created the file. Leave the default setting of 8BIM (Photoshop’s code), unless you know the special file creator ID for the application you plan on using the file with. Many Mac applications have file creator IDs registered with the Apple Computer Developer Services group.
-->Header: This parameter specifies how many bytes of information appear in the file before the image data starts. The default setting of 0 means there is no header. If, for example, you enter a 2, two zeros are entered at the beginning of the file as placeholders. When you open the Photoshop Raw format, you can then replace those placeholders with a header. I recommend leaving the value at 0.
-->Save Channels In: Choose between Interleaved Order and Non-Interleaved Order. The default setting of Interleaved Order stores the color data sequentially by pixels. In other words, in an RGB image, the first byte is red for the first pixel, the second byte is green for the second pixel, the third byte is blue for the third pixel. Non-Interleaved Order stores the color data by channel. In this case, the first byte is red for the first pixel, the second byte is also red for the second pixel. Once the red channel is complete, it then goes and saves the green and then the blue channel.
Your choice depends on requirements of the application that will open the file.
Photoshop and Photoshop Raw Image Format
![Photoshop and Photoshop Raw Image Format]()
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