Techniques for Reducing File Size

This page summarizes file-size reduction techniques for several software applications. File-size reduction strategies are usually directed toward managing the overall size of a package of documents.

NOTE: As a general rule, full-size (non-reduced) copies of important documents should always be archived and backed up: reduced-size copies are not usually meant as a replacement for full versions.


REDUCING FILE SIZE IN PHOTOSHOP IMAGES:

MANAGING LAYERS. A reduced-size Photoshop image, regardless of file type, should always be “flattened” into a single layer. Use the Layer > Flatten Image command.

MANAGING IMAGE RESOLUTION. Use the Image > Image Size command to adjust image dimensions and resolution. Images measuring approximately 5” or 6” in their longest dimension, with a resolution of 150 or 200 pixels per inch, usually represent a good balance between file size and image quality.

CHOOSING THE PROPER FILE TYPE. Generally, though not always, the smallest Photoshop files will be met by using the JPEG file type. Use the File > Save As command. Setting the JPEG quality to “Medium” will represent a good balance of size and quality. In the case of images with large areas of solid color, using the TIFF format (with LZW compression) will usually result in a smaller file.


REDUCING FILE SIZE IN ILLUSTRATOR DOCUMENTS:

CHOOSING THE PROPER FILE TYPE. Illustrator uses two different “native” file formats, AI and PDF. To reduce file size, use the File > Save As command to save your Illustrator file in PDF format. When prompted to choose an “Adobe PDF Preset,” choose “Smallest File Size.”

ADDITIONAL OPTIONS. Refer to this site for a detailed description of Illustrator optimization techniques:
http://helpx.adobe.com/illustrator/kb/optimize-native-pdf-file-sizes.html


REDUCING FILE SIZE IN PDF FILES:

COMBINING DOCUMENTS IN ADOBE ACROBAT. If you choose to combine files into a single PDF, click the “Smallest File Size” icon. Use the “Single PDF” rather than the “PDF Portfolio” option.

PRINTING AS THE SMALLEST FILE SIZE. Open a PDF in Acrobat. Choose File > Print. Select PDF as your printer (Adobe PDF or a PDF Writer). Click the “Properties” button. Under “Default Settings,” choose “Smallest File Size.” Click OK, and then click Print.


REDUCING FILE SIZE IN AUTOCAD DRAWINGS AND MODELS:

PURGING THE AUTOCAD DRAWING. AutoCAD drawings often contain unnecessary information (e. g., unused blocks, layers, text styles, etc.). Type PURGE at the command prompt to eliminate such information. Follow the PURGE command with the File > Save As command.

THE OVERKILL COMMAND. Type OVERKILL at the command prompt to delete certain kinds of information in the drawing, e. g., lines which overlap other lines.

FILE > SAVE AS. Use this command to save a new copy of your AutoCAD file. This will usually reduce file size.


REDUCING FILE SIZE IN REVIT MODELS:

PURGING UNUSED ITEMS. Under the Manage tab, Settings panel, choose Purge Unused. This tool will tend to have a greater effect on Projects than Families.

[APPLICATION MENU] > SAVE AS. Use this command to save a new copy of your Revit file. This will usually reduce file size. Test the effect of checking the “Compact File” option while saving (Click Options in the Save As dialog box).


REDUCING FILE SIZE IN RHINO MODELS:

PURGE THE MODEL. Type PURGE at Rhino’s command prompt.

FILE > SAVE AS. Use this command to save a new copy of your Rhino file. This will usually reduce file size.


REDUCING FILE SIZE IN SKETCHUP MODELS:

PURGE UNUSED. Choose Window > Model Info > Statistics; click Purge Unused. Follow this with File > Save As.

ELIMINATE TEXTURES. A copy of your model saved without textures will be much smaller than the same model with textures.

FILE > SAVE AS. Use this command to save a new copy of your SketchUp file. This will usually reduce file size.

 

 

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AutoCAD: Layers

Every object in AutoCAD belongs to a layer. A layer can be made invisible, causing the objects assigned to that layer to disappear from view (this is called turning a layer off). A layer can be locked, protecting the objects assigned to that layer from accidental erasure or displacement. A layer can be defined as non-printing, so that its objects are visible on screen but do not print.


TO CREATE A NEW LAYER:

Type LAYER. In the resulting Layer Properties Manager dialog box, use the New button to create and name a layer; use the Current button to choose a layer for drawing (newly drawn objects appear on the current layer); use the color swatches to assign colors to layers.


 

TO DELETE A LAYER:

In the Layer Properties Manager dialog box, highlight a layer name and click Delete. If the layer contains objects, it cannot be deleted. Typing PURGE at the command prompt will omit unused layers.


TO CHANGE AN OBJECT’S LAYER:
Use any one of these methods:

Type CHANGE (or –CH). When prompted, select the object(s) and click enter. Type P for Properties; LA for Layer; and then the name of the layer to which you wish to assign the object(s).

OR use the layer pulldown menu in the Object Properties toolbar. Click the object(s); then click the pulldown menu and release the mouse over the layer to which you wish to assign the object(s). Click the escape key to deselect the object(s).

OR click ctrl-1 to display the Properties palette. Click on an object, or a group of objects. Click next to the word “Layer” in the Properties palette and select a layer from the pulldown menu. Click the escape key to deselect the object(s).

OR use the MA (“match properties”) command to assign the properties of a source object, including its layer assignment, to one or more other objects.

 

Photoshop: Layers

Photoshop images can be composed of more than one layer. Layers are like sheets of transparent film on which pixels are painted. Layers may be edited separately and individual layers can be made visible or invisible. Layers can be rearranged; their opacity may be changed; their blending mode can be altered, providing different overlay effects. Be aware that each new layer adds a significant amount of information to your file size.

Once selected, a group of pixels can be copied and pasted within its original image or into a new one. The act of pasting creates a new layer (see Windows > Layers).

A multi-layered image can be flattened to save file space and reduce printing time, but the flattened layers cannot be separated. For this reason, it’s good practice to choose File > Save As before flattening layers in a Photoshop image.


LAYERS PALETTE BASICS:

Make a layer current by clicking its name in the Layers palette. Any actions you perform will (in general) affect only the current layer.

Click on the eye symbol in the Layers palette to make a layer invisible or visible.

Change the opacity of the current layer by sliding the bar at the top of the palette. (Note: you cannot change the opacity of the Background layer.)

Change the display order of layers by dragging them up and down on the list.


LAYER BLENDING MODES:

Normal assumes that the top layer is opaque, unless adjusted by some other means (e. g., the Opacity setting in the Layers palette).

Multiply treats white pixels in the top layer as transparent. 50% white pixels are treated as 50% transparent, and so on.

Screen is exactly the opposite of Multiply. Black pixels in the top layer are treated as transparent.

Overlay combines the effects of Multiply and Screen. 50% (gray) pixels in the top layer are treated as completely transparent. Dark pixels become darker and light pixels become lighter.


LAYER ACTIONS:

To add a new layer: In the Layers palette, choose Layer > New Layer and give it a name. By default, new layers are totally transparent in Photoshop until you paste something onto them or paint on them.

To combine layers: In the Layers palette, choose Layer > Merge Visible to combine the visible layers onto the current layer.

To make the entire image into a single layer: In the Layers palette, choose Layer > Flatten Image.


COPYING BETWEEN LAYERS:

1.  Activate the layer you want to copy from and make the selection. Choose Edit > Copy.

2.  Activate the layer onto which you want to paste the selection. Choose Edit > Paste. Photoshop will automatically create a new layer above the current layer.

3.  (Optional.) Click on the new layer in the Layers palette and choose Layer > Merge Down. (This combines the new layer with the layer immediately below.).

 

 

Rhino: Layers

Every object in a Rhino model belongs to a layer. A layer can be turned off, causing the objects assigned to that layer to disappear from view. A layer can be locked, protecting the objects assigned to that layer from accidental erasure or displacement.

To create a new layer:

Type LAYER to open the Layers panel. Use the New button to create and name a layer; use the color swatches to assign colors to layers; use the Current button to choose a layer for drawing (newly drawn objects appear on the current layer).

To change an object’s layer, use either of these methods:

1. Type CHANGELAYER. Select one or more objects, press Enter, and then select the desired destination layer.

2. Type MATCHPROPERTIES to assign the properties of a source object, including its layer assignment, to one or more other objects.