Gordon's Tech

Monday, October 18, 2004

4 megapixels is enough?

TidBITS: Sense & Sensors in Digital Photography

In short, 4 million pixels carry all of the useful information that you can put into an 8' x 12' photograph. Finer detail than this will matter to technical aficionados making magnified comparisons, and it may matter for scientific or forensic tasks, but it will not matter for ordinary purposes. The same holds for larger prints because we don't normally view larger photographs from only 10 inches away. It holds even for the gigantic images in first-run movie theatres. The digital processing used routinely for editing and special effects generates movies with no more than 2,048 pixels of information from left to right, no matter how wide the screen. The vertical dimension differs among cinematic formats but is typically around 1,500 pixels.

Ok, I'm convinced. In practice 8 megapixels would be great since it gives room to crop still print 8x12.

I want an 8 mpixel sensor with low noise at ISO 1600 and excellent color range.

TidBITS: Colour & Computers

Colour Profiles -- It is possible to spend a lot of time and money calibrating equipment to absurd levels of precision. Since fudge is a basic ingredient of profiles and colour-matching, ICC profiles from different sources will give different results, and there is no way to tell whether you will like a profile without buying it and trying it. Fortunately, most people don't need to profile their printer at all and can get by fine with the default settings. Long ago Microsoft and HP proposed, and the computer industry adopted as a formal standard, a colour-matching technology that's simpler than the full ICC standard while still being sufficient for most people outside the graphics-arts industry. All devices are assumed to be able to produce a range of colours that will fit within a range or 'colour space' called sRGB. A standard set of numbers defines every colour within this space. All devices are supposed to interpret those numbers sensibly. It is the norm for photos on the Web, and most commercial printing services use it, so I've set my Mac to use sRGB by default (ColorSync Utility > Preferences pane > Default Profiles tab > RGB Default pop-up menu).

Most inks on most papers are limited to the range of sRGB, although some do exceed sRGB's range. From some inks a larger colour space defined by Adobe, called 'Adobe RGB,' allows more vivid colours. The difference is likely to matter in print competitions and some corners of the graphic arts trade, but it not clear to me that it would matter elsewhere. Using a larger colour space incurs a cost: it is likely to require 16-bit colour, which requires more storage and processing time...

...In any case, be sure to set the gamma to 2.2. That is the de facto standard for working with colour. The Mac's standard of 1.8 was intended to make a grey-scale monitor look like a printed page.

Years ago, when I was trying to understand color profiles and realizing how ugly this was, I corresponded with an Apple ColorSync engineer. He said: use sRGB everywhere. I've followed that advice. It works. More recent versions of iPhoto even honor sRGB.

I haven't set my gamma to 2.2, looks like I should. I do wish Apple would give up on the 1.8 gamma.

Why device driver software is so bloody awful ...

dcardani: Scanner Suck

Several months ago, Jon Rentzsch wrote an article in his web log about how awful his Canon LiDE scanner was and why he returned it. Apparently it drew a lot of attention, so earlier today he posted a followup about the current state of things. His conclusion:

...after reviewing the marketplace again, I purchased an Epson Perfection 1670 Photo scanner. It requires an external power brick, can't seem to be turned off save unplugging it, but it works and comes with a sane Mac OS X native TWAIN driver. It's not rock, but it's not suck. Apparently, nonsuck is the best the scanner market currently offers.

This hit home with me because I was once involved in creating a scanner driver that wasn't very good. Here's my story.

Several years ago, I worked for a company that got business by lying to its customers and competing on price. They would tell their customers that we could produce a piece of software in an area that we had no expertise in, within a very short amount of time and for very little money. As a result, we got lots of contracts, but rarely produced anything of very good quality, or pleased the customer, except when my exceptional coworkers pulled off a miracle and achieved something beyond their capabilities.

So one day the boss told a potential customer, a Japanese producer of fax and scanner equipment, that we could write them a driver for their USB scanner device for relatively little money in relatively little time. They agreed. Then he came to me and asked 'Can we write a driver for a USB scanner really quickly?', to which I replied 'Hell no.'

I had absolutely zero experience writing drivers of any type, and USB was a new technology at the time. Apple's implementation, I soon found out, had a few bugs, too. Further, while devices like keyboards, mice, and modems had completed specs for USB compatibility, the USB consortium had not yet finalized their scanner specification. (Looking at the USB home page, I'm still not sure it's been finalized.) Oh yeah, did I mention that the scanner was brand new, and the only technical documentation for it was 3 sparse pages of Japanese poorly translated into English?

Needless to say, I spent the next month or two frantically reading Apple's USB docs, manipulating their sample code, and debugging my horrible driver and TWAIN component. In the end I cobbled together something that mostly worked, but did several things the USB Manager docs specifically said not to, simply because I didn't have the time to figure out the correct way to do it.

Fast forward to today where companies are outsourcing much of their software development to companies in 3rd world countries who compete on price, and the situation is just as bad. Actually, it's a little worse because now everyone in that market believes they have to use the cheapest developers available, since they aren't able to make any money on their hardware, and you're pretty much guaranteed to get absolute crap no matter what. (That's not to imply that offshore companies are any worse at writing scanner drivers than those here in the states. Just that when you hire developers on price instead of skill, as I was hired at the time, you get what you pay for.)

Why a business would produce a piece of hardware for which they don't know how to write the software themselves is a bit of a mystery to me, too. It points to the fact that they don't actually design products, they just make something to sell and hope the competition goes out of business before they do. I fully expect to see this trend get much worse in the coming years, as more companies fall prey to the myth that outsourcing development saves money, and the government makes it less and less profitable to hire people for what they're actually worth.

I think it's a complexity problem. The technical world is too complex for most people to figure out, so scams of every sort run wild. Buyers don't seem to care if their purchases work, so why should vendors? As usual the trade magazines (PC World, etc) collude in this deception.

To their credit Microsoft seems to be significantly improving the quality of device drivers.

rentzsch.com: Canon LiDE 30 Followup

A good reference for anyone looking at buying a Canon scanner. As much as I like Canon, their software is awful. It's bad on Windows, but worse on the Mac.

VueScan is a good Mac workaround.

OS X backup report: Retrospect alternatives

Backup on the Mac: Part 2

SuperDuper is mentioned a few times.

Sunday, October 17, 2004

Scantips advice on VueScan

VueScan - Film Scanner software

VueScan is an easy program to use, it is largely automatic, and its defaults are preset for the goal of achieving best results with the most accurate color. If it seems difficult to use, you're likely diddling too much, trust it more, try the defaults. All you really need to set is scan mode and perhaps film type, and it can do the rest. You can size the preview and histogram window as large as you like.

You may sometimes want to tweak Brightness to affect midrange brightness (VueScan Brightness works as a multiplier to Gamma, same as any histogram Midpoint control). But otherwise, the main tone setting you may want to change is the Color Balance. Depending on the image content, one of these may be better than the others.

White Balance adjusts the RGB settings to try to make the image look white, often very desirable. Auto Levels adjusts the RGB settings from the histogram maximum data values, which then map to white. If the scene lighting was sodium lamps or an orange sunset, Neutral probably works best. Images without neutral colors such as gray or white, perhaps images of all green foliage or flowers, may not like White Balance mode, but more nearly typical images (people and places) likely will love it. Then the Auto Black and White Points clip away the specified percentage of the total pixel values. VueScan's defaults clip minimally, if at all, to retain the full data, to NOT discard shadow detail, giving all the range that a negative can give, perhaps a flatter image than you are used to, but it's all there.

You can set the Auto Black and White Points for greater contrast by clipping more, say 0.5% at Black. My own preference is to use the defaults for its magic (good color balance), and tweak contrast later in Photoshop (retaining that data allows choices). For typical scenes, following up with Photoshop Auto Levels (0.5%) is often fantastic. That clipping often enhances image contrast and colors perfectly, but sometimes it's the wrong thing to do. It does discard some shadow detail that VueScan tried to retain.

I'm trying VueScan to see how it will work for scanning a large volume of negatives and prints. I'm outsourcing this work so I want something very simple.

I'm impressed so far. It's very fast and it's very simple. Much nicer workflow than flipping back and forth from TWAIN. It scans directly to the image. Lets me control file naming pretty well. Mac and OS X versions.

A few downsides:

1. In demo mode it watermarks all images. Annoying. I hate scanning for testing and scanning again later.
2. I don't see how to make it use the native TWAIN drivers (if I wanted to do that).
3. Doesn't use a standard windows help file.
4. Install puts it in c:/ drive root. Annoying. I moved it.
5. Had some problems. Apparently known conflicts with logitech mouse.

Cleaning scanner glass

FAQ 3 - Email, Cleaning

My Epson 1660 glass has never seemed clean -- even when I bought it. Finally it occurred to me to search on how to clean the sucker (top and bottom, scanner disassembles easily).

Scantips is an old time favorite web site. They mentioned pure alcohol. Cheapo 70% isopropyl alcohol worked great (pharmacy grade). Patten was clean for the very first time.

Interestingly the scans really don't look all that different.