Guides

Asus EEE PC: Remote On/Off

Apr 19th

Posted by Leonard in Guides | 3,126 views

I originally bought my EEE PC intending to use it as an upgrade/replacement for my current Car PC as it is much smaller, consumes less power, and uses a solid state drive (SSD) for data storage (meaning no moving parts while booting the OS and frontend etc).

There were a couple of problems I needed to overcome though – it would not be a case of simply swapping units over.

The first thing I needed to do was figure out a way to connect the EEE PC to my existing M2-ATX PSU so that the ignition was still able to control the PC turning on and off. On the existing system, this is done using a simple connection to the header on the motherboard. When the PSU recieves the ignition signal, it shorts these two pins together and the system powers on.

On the EEE PC, there is no header that I could connect such a lead to, so I had to rip things open and add one myself…

How to Get at the Internals:

- Remove all screws from the underside of the unit
- On the top edge of the keyboard, there are a couple of springy clips holding it in. Use a flat screwdriver to hold these in and prise the top edge of the keyboard out. The whole thing should slide upwards now and will be attached to the main chassis by a thin ribbon cable.

- You can unclip the ribbon cable to get the keyboard out of the way (carefully!)
- With the keyboard out of the way, remove the black screws holding the top half of the chassis down. You don’t need to remove the two either side of the screen. There are also a couple of plastic clips on the rear – by the screen pivots. These need prising apart (again – either a flat screwdriver or case splitter will be fine). The cover should lift off, revealing the motherboard.

- There are a couple of retention clips on the bottom side of the motherboard which can be released by sliding the motherboard up slightly. It should pop out.
- The VGA port also needs to be levered slight to release the side of the main board. When this is done, it should come loose and if you remove the mini-plug for the fan connector, the board can be removed entirely.

For the purpose of this guide, I was interested in the power button, located near the right hand side screen pivot point. The images below show the switch with what appears to be 5 soldered connectors. With a bit of testing and a flat screwdriver, I determined that the pins which needed shorting together to initiate turn on / switch off were the top two.

So I went about soldering some fly leads and threading them through the chassis, making them secure so they couldnt be pulled off easily.

Putting the EEE PC back together again and plugging it in / connecting the battery, allowed me to test that it all worked properly. Touching the two fly leads together (same as ignition ON) starts the PC up. Once booted, touching the leads together again initiates shutdown (same as ignition OFF).

Next problem is to sort out is the difference in voltage supplied by the regulated PSU (12V) and the input required by the EEE PC (9.5V). Stay tuned…

asus, car pc, eee pc, power button, remote

Honda VTEC Engagement and KMH to MPH Converters

Apr 30th

Posted by Leonard in Guides | 2,352 views

3 comments

On a lot of Japanese Imports the speedometer has been converted from kilometers per hour to miles per hour for ease of use on British roads. This is done by essentially altering the signal that is sent to the speedometer by a factor of ~0.6 (there are 0.6 miles in a kilometer).

The alteration is performed by a little black box which sits at some point between the Vehicle Speed Sensor (VSS) in the engine bay and the Speedometer on the dash. With this little box in place and altering the signal, the speedometer will now display measurements in Miles Per Hour and the odometer will also begin to clock in miles rather than kilometers.

If you want to know how the little black box works, read on. If not, then skip the next paragraph

The VSS sends a series of pulses to the Speedometer and the frequency of these pulses is used to determine how fast the vehicle is travelling. What the little black box does, is alter the frequency of the pulses to produce a resultant difference of a factor of 0.6, thus reducing the reading that the speedometer gives – i.e. it displays the speed effectively in mph.

Welcome back…

Anyway, all is well and good, unless you have a Honda VTEC engine – in which case a little more thought needs to go into the placement of the converter. VTEC gives you a boost of power at a certain RPM and activation is controlled by the ECU. Based on my Honda Prelude, there are three conditions which must be met in order for VTEC to engage:
- The car must be up to normal operating temperature
- The car must be travelling faster than 14kmh (or mph)
- Oil pressure must be high enough

The car is setup as follows:
VSS –> ECU –> Speedo

In theory, you can put the converter inbetween either the VSS and the ECU or the ECU and the Speedo. Either way will produce a reading in mph, but the position used will produce different side effects, especially on Honda VTEC engines.

Method 1:

Fit the converter between the VSS and ECU, in the engine bay.

The VSS is located just on the side of the engine block towards the top of the gearbox. It has three wires coming from it: +ve (yellow/black striped), -ve (black) and the speed signal (orange). The converter needs to fit in-line with these wires.

End result:
-Speedometer reads in miles per hour
-112mph limiter removed
-No VTEC in 1st gear.

Method 2:

Fit the converter between the ECU and the Speedo unit, just behind the actual speedo.

The wires required are located on the green, 10-pin connector towards the top left of the speedometer unit (as you look at it). The wires required are +ve (yellow), -ve (black) and the speed signal, which again is orange (sometimes orange with silver dots for some reason).

End result:
-Speedometer reads in mph
-VTEC in 1st gear
-112mph limiter still in place.

Converter placement schematics

Why does the position matter so much?

Imagine this scenario:
You are accelerating in 1st gear, and given that all the above conditions are met, VTEC will engage at the correct revs. However consider that now you have the MPH converter in place. This is effectively turning the 14mph condition into a limit that is either out of range of 1st gear or right at the top of the rev range where VTEC engagement would be pointless for such a short time.

In other words, by fitting the converter before the ECU, all the subsequent signals related to the vehicle speed are now in MPH internally, but the ECU expects them to be in KMH. By fitting the converter after the ECU, the internals stay in KMH and only the visual output (i.e. the dials) are changed to MPH.

As for the 112mph limiter…well, thats another story

The main point of this post is to hopefully help anyone with a Honda import vehicle who is unable to get VTEC in 1st gear. For more information check out PreludeUK or other Honda specific forums.

112mph, 1st gear, converter, ecu, engage, gearbox, honda, import, kmph, mph, oil pressure, prelude, solenoid, speed sensor, speedo, vss, vtec

Electronic Delay Latch

Mar 9th

Posted by Leonard in Guides | 770 views

1 comment

The Background

A while ago, I built a PC and used an All-in-Wonder Radeon 9700 Pro graphics card. For those who aren’t too familiar with them, read here. They were one of the first cards to require an external power connector to provide extra juice that couldn’t be drawn from the AGP bus.

Coupled with this card, I used an Enermax 435W PSU, which was easily sufficient in terms of power output and was a good, reliable brand. However, I ran into problems with the computer booting from cold.

The fans would start spinning for a brief second before everything died. In my fault finding, I removed the power connector from the graphics card and the system booted up fine and displayed a message telling me to plug the card connector in. Voila, everything works!

Well, except that everytime I want to turn the computer on, I have to unplug the card…not so good.

I came to the conclusion that it was the power supply’s surge protection of some sort kicking in and preventing the card from drawing the power it needed at boot up. (I tried a smaller, no name PSU and it worked fine. However, not wanting to destroy my hardware by using a cheap PSU, I needed a different solution).

The Delay

Since the system worked fine when the power was supplied to the card a few seconds after a cold boot, I figured the only sensible thing would be to simulate this delay electronically. In other words, have a system that sits between the card and the power connector that creates a delay between when I press the power button on the PC to power getting to the card.

After a bit of researching and developing and testing, I came up with the following circuit:

Schematic

Components:

(1x) TIP122 Darlington Pair Transistor
(1x) 47K Variable Linear Pot Resistor
(1x) 100uF 16V Electrolytic Capacitor
(1x) 5.1K Resistor
(1x) 1K Ressitor
(1x) 6V8 Zener Diode
(1x) 1N4001 Diode
(1x) 12V 6A (Double Pole Double Throw) DPDT Relay

Putting It Together

Assemble the circuit using either a bit of stripboard, or if you have access to PCB fabriaction facilities, feel free to use the following mask, but you’ll have to work out where things go for yourself…

PCB Layout

Connect everything up and run a test just to make sure it’s all working as it should. Remember, Yellow = +12V, Red=+5V, Black =0V. Connect it to the PSU and you should hear a definite ‘click’ as the relay latches and turns on. Make sure the transistors aren’t melting and that the capacitors aren’t exploding. Test it with nothing connected to the output just yet – use a multimeter to measure the outputs – they should read 12V and 5V when on.

When you are confident that it is working as it should be, connect it to your graphics card and enjoy never having to mess about with the power connector ever again!

How It Works

When the power button is pressed on the front of the computer (referred to as S1 in the schematic above), the 1k and the variable 47k resistor network allows some current to flow through and get stored in the capacitor.

As this charge builds up, the voltage at the Zener diode begins to rise. When it reaches 6.8V, the diode immediately begins to conduct, turning on the Darlington Pair Transistor.

This transistor pair is isolated from the main power circuitry using a power relay, which is in turn, switched on – causing the main 12V and 5V power lines to effectively connect straight to the graphics card via points A and B marked on the schematic. For reference, the additional diode is in place to protect the transistors.

The delay period can be varied to suit the application using the variable resistor.

Disclaimer

This is only a guide.

You may use the information in the article to help you solve problems you are having with your graphics cards or other related issues, but I AM NOT responsible for anything you blow up or damage. All the work you do is at your own risk. Remember: research and understand what you are doing. If in doubt, don’t do it. If you have any questions, post here or in the forum and I can try and help.

Cheers.

delay, electronics, latch, pc, psu, relay, transistors, zener

Oil Change

Feb 2nd

Posted by Leonard in Guides | 911 views

2 comments

Regular maintenance of your car’s fluids is essential to keep it running as well smoothly as possible – as well as ensuring the engine has a long life.

Amongst all the regular fluid checks like coolant, brake and steering etc, the most important is the oil. The oil stops your car from grinding (literally) to a halt and making horrible screeching and sounds of metal against metal… As well as lubricating everything, it also traps road dirt and filters it out. Basically, its quite important.

The interval between changes will depend on your car (it is usually a good few thousand miles). On my 306, the interval is 6000 miles (diesels like to have more frequent changes – a petrol engine will probably have a longer cycle).

What you need

- Fresh oil. By fresh, I don’t mean go and bore into the earth and refine your own, I mean go and buy some oil of the proper grade viscosity for your engine. The viscosity is denoted by the big writing on the side of the oil container in the form 10W40, 5W30, 20W50 etc. Find the rating for your engine by referring to a Haynes manual or your owner book. Also, make sure you get petrol or diesel oil accordingly.

- A new oil filter. These are smallish pot shaped metal containers (which come in various colours) and are screwed into the engine block and filter out all the crap the oil picks up through different grade filter paper within. The location of your filter may differ – the 306 filter was towards the front/bottom of the engine block shown below (its the white thing!):

Old Filter

- A tub or container. To collect the drained oil – make sure its large enough. The 306 takes 4.5 liters of oil.

Draining the Old Oil

It is best to do the change when the car is slightly warm – not too hot though as you don’t want hot oil splashing everywhere. That would be bad.

First, locate the oil sump and drain plug under your car. It should look similar to the following image:

Sump

Find the correct size socket/spanner and undo the drain plug slightly. Get your container ready to catch the oil and remove the plug fully – it’ll probably go all over your hand, but as long as you don’t drop the plug in the oil container its ok….

Draining

Leave this to drain for a good few minutes, and in the mean time, remove the old filter – it should unscrew by hand but you can buy oil filter removal tools if you really need to. Some oil will fall from the filter once removed so make sure it doesn’t drip on anything important. It’s hard to imagine that this black stuff was once a smooth golden orange color….

Adding the New Oil

Once the oil has been draining for a while and has slowed to a slow drip or stopped altogether, you can replace the drain plug. It is good practice to use a new crush washer when tightening but it is not essential.

To fit the new filter, first rub some oil on the rubber seal washer which runs around the edge of the container (see image below), and screw it into place. Tighten as much as possible by hand – it should not move.

Sealing

All that remains now, is to fill the engine up with the fresh oil. Locate the oil filler cap on the top of the engine (it is usually marked OIL or 710 *chuckle* I make myself laugh…). It best to use a funnel to prevent spillages and make sure you don’t overfill!!!

Final Checks

Before starting the engine, check for any immediate signs of leaks and tighten the corresponding part appropriately…

Now start the engine and check once more for leaks while the engine is running. Stop and leave the car to rest for a minute, and ensuring it is on level ground, check the oil level using the dipstick. Top up if necessary, and you’re done!

dipstick, filter, intervals, level, lubricant, oil change, seal, sump

Rotating Signatures

Jan 13th

Posted by Leonard in Guides | 3,336 views

2 comments

Ever wanted a signature for your forum accounts that changed randomly every time the page was loaded? Not sure how to do it? Well read on and be enlightened…

What you need

Well first of all, you need somewhere to host your images. They need to be in the same directory as each other, and you need control over the naming of the files (so somewhere like Imageshack won’t work).

Your host also needs to be running PHP.

Method:

As you know, to place an image in your signature, you use [IMG] [/IMG] tags around the path of the image. Essentially, what you will be doing in this case, is rather than referencing an image file directly, you reference a .php file which calls a random image for your signature. With me so far?

Ok, first, name all your image files you want in your rotation logically (use 1.jpg, 2.jpg, 3.jpg etc.), then upload them all into the same folder on the server.

Open notepad or any other basic text editor and paste in the following code, courtesy of this site on a single line:

<?php $files = glob('{*.PNG,*.png,*.JPG,*.jpg,*.GIF,*.gif}', GLOB_BRACE); readfile($files[array_rand($files)]); ?>

Save the file as “rotate.php” (remember to change the file extension from .txt to .php), and upload this file to the same directory as your images.

Now alter your signature on the forum as [IMG]http://somehost/sigs/rotate.php[/IMG] you should have a fully functioning rotating signature!

Notes:

Some forums have restrictions on the type of file you can use as a signature image. Sometimes, the .php extension is restricted, which obviously causes problems when using the above method. If this is the case, use the following method: paste the code below into a blank notepad document and save the resulting file as “rand.jpg” :

<?php

Header('Cache-Control: no-cache');
Header('Pragma: no-cache');

$dh = opendir(".");
while (false !== ($file = readdir($dh)))
{
if (preg_match('/\.jpg$/i', $file) and $file != "rand.jpg")
{
$filelist[] = $file;
}
}

srand((double)microtime()*1000000);
$picnum = rand(0, sizeof($filelist) - 1);

header("Location: " . $filelist[$picnum]);

closedir($dh);
?>

Upload this file to the same directory as your signature images. This bit of code basically selects a random jpg image from the bunch you uploaded earlier (similarly to the first method), but since the file itself is technically a jpg (you don’t want it to call itself during the random selection!), there is an exception statement included.

Again, use standard image tags to display your signature:

[IMG]http://somehost/sigs/rand.jpg[/IMG]

And Bob is indeed your Uncle. Any problems, post away.

img, php, random, rotating signatures, script

Fitting a Boost Gauge

Dec 18th

Posted by Leonard in Guides | 2,280 views

7 comments

What is a Boost Gauge and why do I need one?

On cars fitted with a turbo, the air flowing into the engine for combustion is compressed rather than being allowed to flow in naturally (as in a normally aspirated engine). The advantage is that compression means more air can be forced into the cylinders, and a combined with higher fuelling rate, results in an increase in power output from the engine. The pressure of the air (commonly referred to as ‘boost’) is measured in standard units (PSI or BAR) and can be checked using a boost gauge. Boost gauges are useful for troubleshooting if the car is running lower boost than expected and can also be employed as preventative measure: i.e. if you suddenly see the boost drop when driving you know something is wrong.

This guide will give a brief set of instructions on fitting a boost gauge using a few pictures I have from when I fitted one on my 306 DTurbo.

What you need

- Boost Gauge
I used a standard 52mm diameter mechanical gauge for my install. Having a mechanical one means running a section of tubing from the engine bay into the car to measure the pressure. The alternative is an electrical gauge which requires a wire rather than the tubing. In either case, there will also be a few wires to connect to +12V and GND for illumination.

- For the mechanical solution, you should get with the gauge, a fitting kit consisting of a T-Piece, some tubing and maybe other fittings. If you didn’t, then any DIY store should have these things quite cheap. Also, get some jubilee clips to secure the fittings.

- Somewhere to mount the gauge
I got hold of some A-pillar mounts for my gauges but a common place is in the dash itself if you are prepared to do some retrofitting.

In the Engine Bay

The first thing you need to do is locate the boost pipe. In the case of the 306, it is connecting the intercooler to the fuel pump. The pipe itself is quite thick, but the internal diameter isn’t so make sure you get a suitable t-piece. The plan is to split this pipe in half and fix the t-piece in the middle and take a feed to the boost gauge. The image shows the approximate location of the pipe circled red (ignore the orange pipe bit; the picture was taken after I fitted the t-piece and that was added to lengthen the existing pipe):

Fit the t-piece, either using an extra bit of piping like I did, or cut your existing pipe and fit it between the two halves. Secure each joint with a metal jubilee clip to ensure a tight seal so no air can escape.

The above photo was taken from below the joining section looking up – just in case you were confused by the perspective.

You can now connect the boost gauge pipe to the t-piece as shown in the picture, again securing it with a jubilee clip. This now needs to be fed around the engine block and through the bulkhead, into the car. I used the hole and grommet I had already made when wiring my amplifier so this was straightforward. Try not to make any kinks or sharp bends with the tube, as this will impede air flow and give an inaccurate reading on your gauge.

Inside the Car

Now that you have fed the boost pipe into the car, it needs to be routed to wherever you are planning on mounting the gauge. In my case, it was on the driver side A-pillar.

Once there, it should simply be a case of connecting into the inlet on the back of the gauge. At this point, connect up the electrical connections on the gauge as well. On mine there were +12V, GND and LIGHT leads. Obviously connect +12V to a fused live wire (disconnect batter before playing around with power cables!) and GND to a chassis point or GND wire. The LIGHT lead, when switched on, will activate the illumination on the gauge face. You can connect this to your headlight switch for it to come on automatically when you turn your lights on, or as I did, to a custom switch panel so it can be controlled independently.

In the image above, the top one is the boost gauge, the bottom one is an oil pressure gauge (see a different article for that one). The gauges I used are black when off, and illuminated backlight red and white when on. The pillar pods were made for a 306 and fit flush with the pillar. I mounted the switches below the gauges – to the right of the steering wheel so they are out of the way but easily accessible.

Final Words

As always, this guide is based on my own experiences and I’m NOT responsible if you mess something up. Feel free to comment here if you have any questions or if you have any specific issues, use the forum and I can try and give you a hand.

Leonard

bar, boost gauge, fuel, gauge, intercooler, pressure, psi, turbo

Car Audio

Dec 6th

Posted by Leonard in Guides | 714 views

1 comment

Car Audio Systems:
The standard audio on a lot of cars is fine for most purposes, but if you want better sound quality you will have to upgrade. In most cases the first upgrade will be the headunit (the unit in the dash) and this will be connected to the existing speakers. The difference will be noticable, but alongside this, chances are there will be some clipping occurring.
This is because the OEM speakers are not capable of handling the power from the new headunit
or the internal amplification of the headunit is being driven too hard (read: loud).

To reduce the strain on the internal amplifier, an external, more powerful amp can be connected to the system, which in turn will provide much better sound quality. The speakers should also be changed when fitting an amp.

Generally speaking, audio can be divided into three frequency bands: highs (treble), mids, and lows (bass). To get the best sound reproduction, you need to have some form of output for all three ranges. The best way of doing this (imo) is by using a good set of components in the front of the car (handles mids and trebles), and a good quality sub in an enclosure of sorts (thats a different article altogether…) in the rear.

For those who aren’t familiar, component speakers come as a set containing a mid-range woofer and a tweeter to handle the mids and highs respectively. The set also contains a device known as a crossover which separates the incoming signal and routes it to the appropiate component. See image below – the mid woofers are mounted in the door, the tweeters up closer to head level to drag the sound stage upwards, and the crossovers are fixed inside the door itself:

Component Speakers

Unless you really need or want speakers in the rear, my advice would be to avoid them (particularly 6×9s on a parcel shelf) as they will drag the sound-stage behind you (you dont go to a concert and stand with your back to the stage!). Additionally, having 6×9s and a sub in close proximity will undoubtedly cause some damage to the 6×9s and will have no worthwhile benefit.

Amplifiers:
You can get a variety of amplifiers for car audio purposes. The main differences are the number of channels and the output rating. In general, stick to good quality, well known makes. Cheap amps sound like garbage in comparison.

If we stick to the example above of using front components and a sub, there are two feasable options:

Use a 4-channel amp. Use one channel per set of components in the front, and ‘bridge’ the remaining two for a higher output for the sub. This is the method I will go through.
Use a 2-channel amp for the front components and a mono-block for the sub. This is the more powerful method but requires extra cabling and other considerations.

Cabling:
The amplifier is generally secured in the boot as it allows easy dissapation of heat (they can get quite warm) and is quite accesable. The problem is…it needs power from the battery…which unfortunately is in the front of the car…There are five items you need to deal with:

Live cable from the battery positive terminal with an inline fuse to amplifier
Earth cable from amplifier to unpainted section of car chassis
Shielded RCA cables from headunit to amplifier. For sending audio signal from headunit to amp.
Remote control cable. For allowing volume control, auto switch on/off etc from the headunit.
Sheilded speaker cables from the amplifier to the front components and the sub.

The power cable you use is very important, more so in high power installations. If the cable you use is not capable of handling the current draw, it will melt and short on the car chassis potentially causing a fire. You can go through the calculations to determine the max current draw etc, but in general, choose the thickest cable you can. 4AWG is fine for most cases, but do your own research! You can buy amplifier wiring kits from many places and these are fine – just make sure you check the lengths and gauges.

Before beginning any electrical work, disconnect the negative terminal from the battery.

If you are lucky enough to have a pre drilled hole through the firewall then use that for routing the power cable into the car from the engine compartment. If not, you will have to do this youself (make sure you don’t drill into anything important!) and seal the hole using a rubber grommit or other method. When feeding the cable through, make sure the in-line fuse is at the end of the cable closest to the battery.

Under Bonnet Connections

In the above image, the red cable is the power, and you can clearly see the fuse beside the battery. Ignore the other cables I have going through the hole…

Don’t connect the cable to the battery just yet.

You now need to route the cable down the side of the car – its fairly simple to prise away the trim and stick the cable underneath (see image below). Do this until the other end of the cable is in the boot. You may have to be inventive during this step – it depends on your cars design.

While you are at this stage, route the RCA and remote leads down the OTHER side of the car in the same way as you did with the power. Putting them down the opposite side will help eliminate inteference and alternator whine. Also, route the cable for your front speakers in the same manner.

Routing Cabling

You should now have a selection of cable ends in your boot: power, RCA x2, remote and speaker.

Before any of these are connected, secure the amp in place (I screwed mine into the rear of the back seat), and connect the GND terminal to an UNPAINTED point on the car chassis as close to the amp as possible. Remember, the ground cable should be the same gauge as the power cable.

Now you can connect the remaining cables to the appropiate tabs on the amp. The image below shows how I connected them up:

RCA’s in for channels 1,2,3 and 4.

Amp Connections
From left to right:

Channels 1 and 2 connected by the white cables to the front component speakers (double check you get the positive and negative the right way round)
Channels 3 and 4 are ‘bridged’ and connected to the subwoofer. Again, check positive and negative.
Thick red power cable (connect this last)
Thin red remote lead connection
Ground

There should be nothing left loose in the boot.

You can now connect the live end of the power cable to the battery positive terminal. It may be wise to use a distribution block for ease of use, but it is not essential.

Double check all connections and reconnect the negative terminal block to the battery. Test out the amp, make sure everything works correctly, and fine tune the settings using the crossovers, high pass and low pass filters etc on the amp to suit your music.

Final Words:
There are many different ways of connecting and configuring your system, this guide shows just one of them. Feel free to leave a comment here about anything contained in this guide, or if you have any specific questions or problems with your installation, post up in the forum and I can try to help.

Leonard.

Note that this is only intended to be a guide, and as such, I can’t be responsible for any problems you come across by following it. Use your common sense – if you aren’t sure, ask someone for advice or get someone who knows what they’re doing to help you or do it for you.

amplifier, bass, battery, car audio, component, crossovers, firewall, frequency, routing, speakers, subwoofer, wires

Basic HDR Effects

Dec 6th

Posted by Leonard in Guides | 587 views

No comments

What is HDR?

HDR (or High Dynamic Range) is defined as: “A lighting procedure designed to emulate the way that light levels in the real world vary over an enormous range.” In other words, the pictures you take on your digital camera capture the light at the particular instant you take the shot. This could be referred to as an LDR shot (Low Dynamic Range) and although looks fine, with a bit of processing, can look a whole lot better. HDR tends to bring out detail that previously wasn’t visible and adds a certain depth to an image.

There are two methods which can be used to create a HDR image. In each case, to process and create the end result, you need a total of three pictures which differ from each other in exposure only. The exposure of each image will depend largely on the content of the shot, but as a rough guide, use -2, 0 and +2.

Taking Three Individual Shots

Using this method, you will invariably get a better quality HDR image with less noise. If your camera has the capability of setting automatic exposure brackets, use this method to obtain your three images at -2, 0 and +2 preferably in RAW or TIFF format.

If your camera does not have the automatic bracket exposure feature (most compact point and shoot cameras tend not to have this), it’s not a problem. You will simply have to generate the images manually.

Generating Three Images from a Single Shot

- Take your picture as normal – try to get the cleanest shot you can – noise becomes a problem using this method.

- Using a suitable image editing software package (eg. Photoshop), create two extra images with a + /- 2 exposure setting. In Photoshop CS2, this can be found under “Image > Adjustments > Exposure…”

- You will now have three photos which, to the eye, look like they have been taken at different exposures. The problem lies in that when the HDR generation stage is carried out, the software reads the EXIF data from the image files (information about the image based on the original camera settings). Since all three images you have were generated from the same original, they will all appear to be of exposure 0 to the software.

- To overcome this problem, use any freeware EXIF stripper to remove this information from your images. This will force the HDR software to read the images at ‘face value’.

Here are the images I ended up with for this example:

Exposure -2:

Exposure 0:

Exposure +2:

It is now time to create the HDR image.