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How to prepare an image file


Scanning and Resolution

A high quality 35mm film may contain over 70MB of data, but in most case a 2700dpi scanner (3700x2550 pixel, around 28MB) can capture most of the information on the film. 2700dpi is equivalent to 106 pixel per mm, it can resolve over 50 lines/mm, that is comparable to normal 35mm camera system.

When come back to our normal needs, 300dpi is good enough for normal viewing. A 4"x6" print at that resolution is equal to 1200x1800 pixels, which is only 6.5MB.

If you are scanning from a photo or film scanner, you should scan at the native resolution, that is same or less than the optical resolution of the scanner. Don't perform any interpolation, it will not increase the resolution but only make it worse.

For 35mm slide output, please make sure the aspect ratio is close to 3:2, otherwise black borders will result.

Typical image size of some media.
High quality 35mm film scanner 4000dip file size 60MB (TIFF)
Kodak Photo-CD 3072x2048 pixels file size 18.8MB (TIFF)
10MP Digital Camera 3888x2592 pixels file size 28.8MB (TIFF)

Color and Contrast Adjustment

We prefer you do your own adjustment before sending the files to us as we have no idea how your original image look. A good monitor calibration is important for obtaining the best result, please use sRGB monitor profile.

If your monitor can adjust color temperature you should set it to 5000K-6500K, if you are using Photoshop you can go to the "preference"-"monitor adjustment", set the gamma to 2.2. Enter the calibration manual and follow the instruction to calibrate your display.

You may also check here for a test chart to calibrate your monitor.


Image compression

For photographic image, JPG is good for most applications. A 28MB file can be compressed to around 1.5-2.5MB without noticeable loss when viewing at 100% on monitor. This is our recommended file type when sending through Internet. If you are sending CD, you may save the file in TIF or BMP format.

Output Resolution

We employed a high quality variable resolution film recorder with 36 bit colors, files can be output at up to 8K lines resolution. For bitmap files, we will output at your file's original pixel size, a picture of 2000 pixels wide can provide quite good result.

Sending files

For files smaller than 3MB/frame, Internet is a good tool. For larger files, please use CD/DVD.

Please contact us at chling@accura.com.hk if you have any questions, we are very flexible in many aspect, please feel free to ask for special arrangement.