* Anna Backstrom [10-06-06 15:01]:

I need to use a photo editor to edit some photos that will be put on t-shirts. The person that does the t-shirts uses Adobe Photoshop and I was wondering if the edited photos from this program will be compatible with Photoshop.

I would think that there would be no problem as long as you save the photos in a format that photoshop can read.

Anna Backstrom wrote:

I need to use a photo editor to edit some photos that will be put on t-shirts. The person that does the t-shirts uses Adobe Photoshop and I was wondering if the edited photos from this program will be compatible with Photoshop.

Thanks

Anna

You shouldn't have any problem, you'll just need to save the file in a different format as I don't think Photoshop can read GIMP's XCF files. If the Photoshop user plans to do more with the file once they get it, or if you plan to be exchanging it back and forth, then your best bet would be to save it as a PSD file. If they are just taking your file and printing it directly then you could export it to PNG or JPG (if you need the file to be small).

Mike

Apologies - forgot to "reply-all"

My advice would be to save your files in TIFF format. If you enable LZW compression, the file size will be significantly reduced without losing quality (unlike JPEG, and to some degree PNG).

I'm not sure what process your printer is using, but if it's just a full-color transfer, a resolution of 200 DPI will be sufficient.

Chris

On Oct 7, 2006, at 7:25 PM, Chris Mohler wrote:

Apologies - forgot to "reply-all"

My advice would be to save your files in TIFF format. If you enable LZW compression, the file size will be significantly reduced without losing quality (unlike JPEG, and to some degree PNG).

PNG is just as lossless as TIFF with LZW compression. There are ways of lossily compressing PNGs but they are non-standard and GIMP does not implement them as far as I know.

Either will suffice in this case as photoshop reads both, though its support for PNG in certain situations (mostly having to do with 16 bits per channel images) is sub-par.

TIFF is another good option, however the Wikipedia entry for PNG says it uses a type of lossless compression. Have I missed something here? I am very curious to know the answer as I have started to save my completed photographs as PNG because I thought there was no penalty for doing so.

Thanks,
Mike

http://en.wikipedia.org/wiki/PNG

Chris Mohler wrote:

My advice would be to save your files in TIFF format. If you enable LZW compression, the file size will be significantly reduced without losing quality (unlike JPEG, and to some degree PNG).

I'm not sure what process your printer is using, but if it's just a full-color transfer, a resolution of 200 DPI will be sufficient.

Chris

Mike Foster wrote:

TIFF is another good option, however the Wikipedia entry for PNG says it uses a type of lossless compression. Have I missed something here? I am very curious to know the answer as I have started to save my completed photographs as PNG because I thought there was no penalty for doing so.

I agree with you, Mike. My understanding is that the different compression settings of PNG only effect how rigorously (and time consuming) the compression algorith is; i.e., that all PNG files are losslessly compressed.

-------- "It is amazing what you can accomplish if you do not care who gets the credit." -- Harry S. Truman

On 10/7/06, Saul Goode wrote:

Mike Foster wrote:

TIFF is another good option, however the Wikipedia entry for PNG says it uses a type of lossless compression. Have I missed something here? I am very curious to know the answer as I have started to save my completed photographs as PNG because I thought there was no penalty for doing so.

I agree with you, Mike. My understanding is that the different compression settings of PNG only effect how rigorously (and time consuming) the compression algorith is; i.e., that all PNG files are losslessly compressed.

PNG supports indexed and grayscale color modes which aren't lossless, however by default the PNG is entirely lossless

On Oct 8, 2006, at 5:21 PM, Jozef Legeny wrote:

PNG supports indexed and grayscale color modes which aren't lossless, however by default the PNG is entirely lossless

That is a bit of a weird definition of lossless. If you save an RGB32 image as an indexed or grayscale PNG then yes, you've lost information. But that is inherent to grayscale and indexed images. You should have saved that as an RGB32 image, which PNG fully supports. In this case it isn't PNG throwing data away (like JPEG does), but the image editor (GIMP) converting to indexed/grayscale and then saving that. Indexed and grayscale modes in PNG are just as lossless as its non-indexed modes.

However like I said there are methods of tuning the PNG's compression to be lossy, and yet still be PNG-compatible. No image editors that I know of implement these methods, however. (http://membled.com/work/ apps/lossy_png/).

When I open a file in GIMP, and save a copy as PNG, open the them up side-by-side: the colors habe been altered in the PNG (albeit slightly). I consider that "loss", and I don't trust PNG for photos. Web graphics - no problem. PNG beats the hell out of GIF. It just isn't ready for pre-press yet, IMO.

Chris

On 10/9/06, Chris Mohler wrote:

When I open a file in GIMP, and save a copy as PNG, open the them up side-by-side: the colors habe been altered in the PNG (albeit slightly). I consider that "loss", and I don't trust PNG for photos.

It would be loss if the colors had changed; however they haven't. I just checked by saving a PNG which had chosen colors in certain areas, then loading that PNG and comparing the color values to the original. No change. Conclusion: monitor display artefact or your hallucination.

David Gowers wrote:

Conclusion: monitor display artefact or your hallucination.

... or gamma correction? Unless you consider this an artefact.

HTH, Michael

I stand corrected.

My PNG *does* match the original exactly, pixel per pixel. I wasn't hallucinating - just mistakenly opened the wrong two files for comparison.

Chris.