Editing digital pictures

[AndreyD]

I need expert edvise, probaly the question not new.
I've heard somewhere that if your camera do shots only in JPEG format, if you then later whant to edit them on your computer, it's better to convert them to BMP, do then all alterations to the picture and then, if you need so, convert it back to JPEG.
Is this true?

[Roger_Cavanagh]

Andrey,

You are referring to the data loss caused by compression in the JPG format. You are correct that this can be a problem. If you repeatedly edit and save a JPG more and more data will be lost and compression artefacts will appear.

BMP is one option for lossless saving, but I would investigate what others are available for your preferred photo editor. Most editors have their own format that is best to use because they may have features (e.g., layers) that will also be saved. You can, if you wish, save a JPG version once all edits are finished.

Regards,

[AndreyD]

Thank you.
So, if I understood correctly, all changes to a picture better to perform not in GPEG format, but, say, in BMP?
Then, I can leave it in BMP and print it also as BMP.

I mean, my consern is that to alter picture (unsharp, exposure, colore, etc.) better to do with a file not in JPG but in BMP format?

[AndreyD]

I use Photoshop and ACDC photo editors

[Roger_Cavanagh]

AndreyD wrote:
Thank you.
So, if I understood correctly, all changes to a picture better to perform not in GPEG format, but, say, in BMP?
Then, I can leave it in BMP and print it also as BMP.

I mean, my consern is that to alter picture (unsharp, exposure, colore, etc.) better to do with a file not in JPG but in BMP format?

You say you have Photoshop, so I would save files in PSD format while you are editing. You can print from PSD as well.

Once you have completed editing, you must choose whether to save space by saving a JPG version and deleting the PSD. You can open and print the JPG without losing any more image quality, but, of course, you not not edit and re-save this JPG.

I don't have ACDsee so I don't know its capabilities, but I cannot imagine that it would compete with Photoshop.

Regards,

[henkbos]

Is it not better to save in TIFF? PSD files can be quite big!

[Longwatcher]

I have found it is best to save the original in TIF if from RAW before going to photoshop. If it starts as Jpeg, then I keep it in PSD format while editing and if I may make further changes later I keep it in PSD. I do this because if you save to TIF you lose the layer information of the PSD file.

Jpeg should only be used for the last step in the process, producing a digital image for distribution.

If there is a remote possibility that you might do further editing in the future, but don't think you will, then saving in TIF is better then saving in JPEG.

I typically save the edited photo in PSD for personal Archive and jpeg for images that go to others, but conversion to jpeg (or back to jpeg) is always the last step.

The key is balancing storage/transmission (file size) versus quality loss and distribution method.

Jpeg = low file size, loses information (the smaller the file size the more data it loses), standard format

TIF = med-large file size, no loss of information, no layers, common format, but not all people will be able to view

PSD = large file size, no loss of information, maintains layers, propietary format (meaning only people with photoshop (or compatable) software can view)

BMP = very large file size, This is the information on a pixel for pixel basis, no layers, standard format
(note because of layers it is possible for the PSD file to be larger then the BMP, but highly unlikely)

[AndreyD]

Thank you! Your advices completely satisfying for me now :-)