CD Pressing Information

I am sorry if my words come over too harsh. They are never meant negative. I understand the team has a huge work load and we should not be hassling to get any special treatment.

When I said there is not time to do something like adding a matrix type to artwork, it is based on the acknowledgement that even a small change takes a lot of work to complete and there are far more important tasks.

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Thank you 1000 fold. This is very much appreciated.

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:raised_hands: :raised_hands: :raised_hands:

And still engages with the community constantly :exploding_head:

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Clearly you people have no regard for my free time. :smile:

I’ve started adding matrix to my CD scanning routine. Hopefully someone finds it usefuly.

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I’ve been sitting on this link for a couple of years now, but I think everyone in this thread may find it useful:
http://wiki.redump.org/index.php?title=List_of_SID_codes

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…continuing the “copy stand post” above (as promised)

The “reprokid” has only a 30x30 base and its lighting arms have a maximum incline of 30°. This might be enough, but I’ve bought another candidate:

It has a 40x40 base. Its arms can be positioned at any angle, so it’s no problem moving the lights out of the “danger zone”.
I took some test pictures, but it will take a few more tries before I get satisfactory results. And the camera isn’t quite what I was hoping for… a Canon Powershot SX130 IS (marginally better than my own, but for now that will do)

I also added a raw image. It shows quite badly distorted edge areas, but it should be possible to improve that. I didn’t manage to set the focus manually - the pictures were taken with autofocus…

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Thanks for the update. Very interesting topic and insights. The distortion issue is indeed a problem. Let us know when you have new details to share.

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The distortions are due to the camera lens and the maximum resolution of 4000x3000 pixels doesn’t leave much room for manoeuvre. But it should be possible to do better. :slight_smile:

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As I have started scanning CD matrix numbers, I’ve found that some discs (particularly older ones) are very difficult to scan - the codes are much fainter than on other discs, and only visible to the eye when I hold it to the light at a particular angle. Anyone found any tricks for scanning those?

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That’s great!

No, I don’t have any special trick either, except maybe adjusting the brightness and contrast of the image.
I haven’t had any that I can’t read at all. And for “microscopic” SID codes I also have my microscope. :slight_smile:

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A cheap USB microscope is an absolute must.

Random example that I own: https://www.amazon.co.uk/gp/product/B07DRGR6LX/

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Well that might be fun but…my interest/willingness for this endeavor falls in between the levels of “do an extra scan” and “buy more gear”. :smiley:

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A scanner can’t get to this level of detail. Even at 1200dpi it is hard to read. It is also quicker to use the microscope than a scanner.

As to fun - this thing is great on things like moss or fossils. It is a great little toy way beyond reading CDs.

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These mould SID codes in particular are often invisible on scans. But it is also possible to see them with a good magnifying glass.

I’m using the “replace color” option in Photoshop for the matrix runout to make it stand out more (works for most CDs) and the super-makro mode of my smartphone (p30 pro) for the mould code. Helps a lot.
But the microscope idea is great too. :grin:

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I recently bought this one based on your suggestion and it’s done a great job of reading tiny codes. It also works great for plants, bugs, and other little things.

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I had to resort to using my Nikon DSLR with to 105mm macro lens… primarily due to the necessity of controlling the shape, direction, area, angle, etc. of the light source. Back in the 1980’s and 1990’s various CD manufacturing plants, used various different methods of engraving a matrix code on a particular production run of a CD.

So, some of them possibly used a YAG laser to cut the letters and numbers as a few dozen dots, or parallel lines… or literally just drawn out the edges of the letters and numbers as vectors.

Some of them look like someone carefully scratched the letters and numbers into the surface of the stamper by hand, with a sharp metal object.

Anyway, depending on the microscopic shape, of the area, of the characters, the angle of the light is most important, so plan on moving your light(s) and camera around every time for every disc. Also get used to constantly adjusting the aperture of your lens too… because you’re basically taking a photo in the mirror, and with a large depth of field you’re going to just get a picture of your light source.

(Also, you’ll need to keep decreasing your shutter speed, and cranking down your ISO, so you’re not constantly blinding yourself by taking a photo of your light source in a mirror…) (but only sometime when the reflection angle is small… many times the angle between the light and the lens is large… and you’ll need to increase your shutter speed, because now it’s dark…)

So… what works pretty well, maybe 70% of the time, is a diffuse light box surrounding as much of your CD as possible. You can improvise with any large white or gray surface (paper or cloth, etc.) that’s evenly lit. Keep in mind that you will see the shape of the light in the reflection on the CD. If you put a bright or dark object nearby, you’ll see a bright or dark stripe on the CD…

So… this doesn’t work for some matrix code engravings… so in those cases I use a white LED flashlight (point source), and with the camera on a tripod (same as above if I didn’t mention) move the camera, CD, and flashlight around until the matrix is clearly visible. I have a remote control shutter release for my camera, with makes it so much easier to do…

I’ve experimented with a green laser pointer too, sometime that works better, and other times worse. It is really good if you want to get a clear photo of which areas of the CD have engraved data, and which areas have been left unwritten. (In a light box, the surface of the CD will appear a smooth continuous gray color – with a laser pointer you get a bright stripe on a dark background, but within the stripe you can clearly see a high contrast “grain” where the lands and pits are engraved)

So… on some CDs, none of the above work, because you need the light reflected almost exactly perpendicular to the surface of the CD. For those CDs I need to use a ring flash. (It works for other CDs too, but mine was built back in 1972, and is a pain to use, and I can’t see what I’m doing, and the capacitors take like 15 seconds to recharge after each flash…) The reflection angle is so narrow, the lens is physically in the way of the light. You can tilt the camera or CD a little bit to make this easier, but you will introduce distortion and blurring…

… unless you have a bellows or tilt-shift lens.

I forgot to mention: I mount my camera on a tripod, and set it level to the surface on which I’m placing the CD, so that all parts of the CD are exactly the same distance from the camera lens. (i.e. the image is flat) I open the aperture as wide as possible, so only the surface of the CD is in focus, and the reflected light source is out of focus. (I even use a bubble level to check.)

… And then my life gets complicated and I don’t upload the photos for a year…

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I think @foxgrrl just summed up perfectly why I don’t take photos of SIDs. :rofl: Just go for the strong light to spot it, and a microscope to read it. And even then I’ll cross check with other data to check what I read makes sense. The classic example being misreading IFPI L046 as L045 due to the fonts.

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For mastering SIDs, I had the best results with high-resolution scans (I use 1200dpi, but 600dpi should be fine, even for the tiny ones)
Mould SIDs are more tricky, but i found a good way to do it too:
I locate it with the help of a magnifying glass, and then I take a “photograph” with the microscope (lighting can be varied until it is visible).

Of course, a few problems remain. Mastering SIDs may be hidden under a bulging ring or may have been distorted during duplication. If written in an area that is not metal plated on the finished disc, the mastering SID may be invisible, or partially invisible, which can lead to misinterpretations, as @IvanDobsky mentioned.