Burned Image File And It's Original.

[jasperita@yahoo.com]

I have Easy CD Creator Version 5.1. pre installed on my Gateway Computer. CD-ROM: 16X10X/40X Recordable Rewriteable CDRW pre installed on my Gateway Computer. I am burning data CD-R's. Image files. I transfer my digital photos to my hard drive. I have Jpeg's and Tiff files. I do not change their size, I just transfer them from the camera and then start a data CD project. My question is this. When I look at one of the photos I have burned, it looks slightly different from the original file on my hard drive. The burned version looks just slightly more contrasty. I compare both photos side by side in Photoshop Elements. I take them down to pixels...the same spot...the same pixels, and the light pixels of the burned picture look just a bit lighter and the medium dark pixels look just a bit darker. The pixel structure is identical. My Photoshop teacher said this would be identical because burning, in the end, is just numbers. The burned CD is just a numerical copy of the original CD. But my burned CD is just a bit contrasty. Some people told me to burn slower. Everywhere I read it says, you can't burn too slow! I was burning them at the fastest I could, 16X. I re-burned a photo at 8X and compared all of them, original, 1st burn at 16X, and 2nd burn at 8X and the 8X photo looked less contrasty, but still not an exact match of the original. But it did come very close to the original. I'm not familiar with much of this at all. Could the burn be compressing the image file? Could the color profile be changed after burning or when it is opened from the CD? Could it be my soft wear? Could it be my burner? Could it be the CD-R? I really am treading water here. Can not find anything on this.

Any ideas on this? Thank you Very Much for your help.

[Brendon]

Hello,

 

When you burn a data file to a CD, an exact copy of the file is written on the CD. If you copy it off again and do a byte-for-byte compare of the original file and its copy you will find they are identical.

 

I know this in practice, because I often do byte-for-byte comparisons when testing things, so it's not just a belief I hold. Try it youself. Get a file compare utility (the old Micro$oft COMP.COM works very well) and compare a CD copy of one of your files with the original file.

 

To compare images visually, you really need to be able to display both of them on the same screen at the same time with the same software. If you do otherwise it's too easy to be misled, no matter how careful you are.

 

>"Everywhere I read it says, you can't burn too slow! "

 

That's quite WRONG, I'm afraid. In the early days the slower you burned a CD the "darker" the burn would be, and the better chance you would have of getting a read off it from an insensitive player. Not so today.

Again if your system could not deliver data fast enough to the drive, the drive would suffer a "buffer underrun" and the disc would be ruined. For these reasons, slower was considered better. NOT NOW!

 

Modern drives calibrate their power against the disc they're burning on, and are optimized to burn best in the mid- to upper-ranges of their permitted burning speed. If you shift too much from the optimum you're more likely to get error(s).

 

Finally, burning slower or faster isn't going to change the contrast of an image file. You either get an identical file or you get an error reported. The bits which are written in each sector of the disc must add up to precisely equal a checksum written at the end of the sector. The file must be identical, or it's a different file and that's not allowed when burning a copy to CD.

[d_deweywright]

Hello,

 

When you burn a data file to a CD, an exact copy of the file is written on the CD. If you copy it off again and do a byte-for-byte compare of the original file and its copy you will find they are identical.

 

I know this in practice, because I often do byte-for-byte comparisons when testing things, so it's not just a belief I hold. Try it youself. Get a file compare utility (the old Micro$oft COMP.COM works very well) and compare a CD copy of one of your files with the original file.

 

To compare images visually, you really need to be able to display both of them on the same screen at the same time with the same software. If you do otherwise it's too easy to be misled, no matter how careful you are.

Let me agree with what Brendon has said. The files will be identical. As another test, which Brendon also proposed, open both files in your image editing program at the same time. Zoom in on an area where you can find the same pixel on both images. Have your image editing program give you the values of that pixel, and surrounding pixels. Compare the values of both images. The should be identical between images.

 

The other test would be to have someone else open both images in your image editor and position them without you looking, and arrange them you cannot tell which image is from the CD, and which is from your HD. (This needs to be done without you looking.) Basically, it's a single-blind test. Now without any knowledge of which image is which, can you see any difference?

 

Good luck!

[jasperita@yahoo.com]

This is cracking me up. I was comparing both pictures on the same screen, the same time, the same softwear. It was more like I was seeing both pictures through a different glass or something. Fast forward to today! Maybe changing the burning speed changes a filter or something. I have 16X, 12X, 8X, 4X, 2X write speeds. I decreased to 8X which would be exactly the middle. Today I could not see a difference!!!!! I compared sizes and values. The sizes had all increased aprox. from 3.54MB on the original to 4.38MB on the burned copy. The values of each identical pixel was exactly the same on both! But today the originals and their burned copies looked THE SAME and I couldn't have told them apart!!!! So Thank You very very much Brendon & d deweywright for your help! And if I have to come back I hope, my next problem is less murky than this! Thank You