On Scanning (part II)

Butte, Wyoming

Part II of II

In my previous post, I described my current process of scanning slides and negs into RAW DNG files. In this post, I describe the post processing pass to convert the DNGs to more “baked” forms of files: TIFFs and JPEGs.

Once a basic raw scan is available as a DNG, there might be several ways to “develop” it. Currently, I am using VueScan to reprocess the RAW files into 24-bit losslessly-compressed TIFFs. The TIFFs can then be post processed further using an image editor or batch converted to JPEGs, etc. In the future, I might use a different technique, and having the RAWs around means I can “redevelop” them again if I decide later that there is a better way to do it, ideally without having to scan the slides ever again.

I usually postprocess to Adobe RGB color space for TIFFs with a color profile embedded in the file. There are other color spaces possible, but from what I have read it is best not to use too large a color space for your images. Adobe RGB seems like an all around good compromise, and has the benefit of wide support, especially in DNG files. I have a color profile for my laptop display and the results are fairly accurate, to my eye, from VueScan’s post processing.

Here are the settings that I use:

- Task: Scan to file
- Source: File
- Files:
- Media: Slide film
- Batch scan: List
- Batch list: 1,2,3,4,5,6,7,8,9,10,11,12
- Multi page: off
- Frame number: 1
- Preview resolution: Auto
- Scan resolution: 3200 dpi
- Rotation: None
- Skew: 0
- Mirror: on (very important to prevent work in postprocessing!)
- Auto scan: None
- Auto save: Scan
- Auto print: None
- Scan from preview: None
- Lock film base color: off
- Default options: off

- Crop size: Maximum
- Multi crop: None
- Lock aspect ratio: off
- Border (%): 0
- Buffer (%): 0
- Preview area: Default
- Default options: off

- Infrared clean: Light
- Restore colors: off
- Restore fading: off
- Grain reduction: None
- Sharpen: on
- Default options: off

- Color balance: White balance
- Black point (%): 0
- White point (%): 1
- Curve low: 0.25
- Curve high: 0.75
- Brightness: 1
- Brightness red: 1
- Brightness green: 1
- Brightness blue: 1
- Slide vendor: GENERIC
- Slide brand: COLOR
- Slide type: SLIDE
- Scanner color space: Built-in
- Printer color space: ICC Profile
- Printer ICC profile: path-to-ICC-profile
- Printer ICC description:
- Printer IT8 data: printer.it8
- Film color space: Built-in
- Show IT8 outline: off
- Output color space: Adobe RGB
- Monitor color space: ICC Profile
- Monitor ICC profile: path-to-ICC-profile
- View color: RGB
- Pixel colors: off
- Default options: off

- Default folder: path-to-scan-folder
- Printed size: 8x12in
- Auto file name: on
- TIFF file: on
- TIFF file name: @.tif
- TIFF size reduction: 1
- TIFF multi page: off
- TIFF file type: 24 bit RGB
- TIFF compression: On
- TIFF DNG format: off
- TIFF profile: on
- JPEG file: off
- PDF file: off
- OCR text file: off
- Index file: off
- Description:
- Copyright: my-name
- Date: desired-date
- Log file: on
- Log file max size (MB): 2
- Default options: off

- Language: English
- Crop units: inch
- Printed units: inch
- External viewer: off
- External editor: off
- Browser: mozilla
- Graph type: Image
- Button 1 action: None
- Button 2 action: None
- Button 3 action: None
- Button 4 action: None
- Auto refresh: on
- Display raw scan: on
- Splash screen: on
- Histogram type: Linear
- Animate crop box: on
- Thick crop box: on
- Add extensions: on
- Substitute date: on
- Warn on overwrite: on
- Warn on not ready: on
- Warn on no scanner: on
- Exit when done: off
- Beep when done: off
- Beep when auto eject: off
- Use temp file name: off
- Anti alias text: on
- Anti alias image: on
- Enable density display: off
- Enable raw from disk: off
- Disable scanners: None
- Enable sliders: on
- Enable spin buttons: on
- Enable popup tips: on
- Enable sample images: on
- Startup tip: 0
- Image memory (MB): 2048
- Window maximized: off
- Window iconized: off
- Window x offset: 96
- Window y offset: 41
- Window x size: 1728
- Window y size: 1080
- Font size (pt): 9
- Option panel width: 340
- Default options: off

Click the “@” sign by the “Files” setting and point VueScan at the first file in the series that you want to postprocess (note: DON’T forget to do this or you will likely process the wrong files–VueScan defaults to the first likely RAW file it finds in the folder, and that may not be the one that you want to start with). I use the “List” setting under “Batch scan” for the post processing pass, because there is less likelihood of reprocessing images you weren’t intending to (VueScan’s interface could be better on this, to be sure). Then set the Batch list to the set of frames to process (usually the entire set, or “1,2,3,4,5,6,7,8,9,10,11,12”).

Under the Crop tab, you may want to adjust the “Buffer (%)” setting to the same figure as you used in “Border (%)” (if you upped that figure from 0 during the scans) to avoid computing too much black into the color settings calculation (auto white balance).

Make sure the “Frame number” setting is set to 1 and hit “Preview”. All the files will be read in and preview images generated. Here again I give a quick look over to make sure that everything looks OK, paying attention now to white balance, exposure, correct cropping, mirroring, etc. This is the time to make adjustments if necessary.

Once satisfied, I hit “Scan”. The post processing is much faster than the scanning of course, since it is only reading in the RAWs from disk, applying the chosen post processing effects, and spitting out the baked files. Now the RAWs are around 100MB each. On my 2 GHz Core 2 Due laptop, it takes around 2 minutes to process all 12 files in a batch. Afterward, there are 12 new TIFF files in the output folder. These I examine with an image viewer and, if necessary, do further post processing in a separate image editor, possibly after refiling the current set of slides and whilst scanning a new batch of 12.

With the slide loading, preview, scanning and the post processing, one batch of 12 takes around an hour to do. My mode of operation is to load a set when I get up first thing in the morning, another set or two when I get home from work, and a final set or two in the late evening. Weekends if I’m around I can process more sets, while puttering around the house or doing other tasks.

Using this process I am slowly working my way through years and years of negatives and slides, and getting great results.

2 thoughts on “On Scanning (part II)

  1. Hi,

    Great guide. Just curious why you select mirror on at both stages? Doesn’t this just flip the image if you’re inserted it upside down on the scanner?? And in your output settings you have it set to 8x12in printed size; is that essential or set to your own preference? For example, what would happen if that was set to Scan size at the RAW stage?

    Thanks in advance.

    • Hi Gareth,
      Sorry for the late reply. Somehow I didn’t catch this comment until I reviewed the comment queue today.
      As far as the printed size setting, I think that just sets some meta data keywords in the TIFF header. It doesn’t actually affect the RAW scan. It’s not essential. The resolution setting is what determines the scan resolution.
      As far as the mirror setting is concerned, I found that I needed it or the images ended up flipped. I’ll have to review again the settings for both first (slide) and second (raw) scans, but I suspect that, like printed size, it doesn’t affect the RAW scan, and therefore the image is only flipped once.

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