Photo Problem - Can Someone Take A Look??

[Karen Thompson]

Hi everyone, I hope I find you all well.

I wondered if anyone could have a look at the attached photos for me (hopefully I attached them OK) and tell me where I might be going wrong? I’m currently tearing my hair out with this one (and if I’m honest "anything" photo related).

The images were engraved on laser grade ply. My process was to use the original jpg file (was given a scanned copy of the image to begin with but was really awful quality).

Opened the file in Corel Photo-Paint cropped it - resampled it – removed background – vignette – saved.

Then: Imported it in to Photograv did the do with that (chose birch settings) saved etc etc…..

Then: Imported it into the laser's software (Lasercut 5.1).

The 1st image was saved/cut at 5"x3.5" and done using 400 speed and 17 power but needed 2 passes. So I’m thinking it looks OK but would probably look even better if it were bigger. Did “all” the above again but resampled it to a bigger size 7"x5". Used exactly same speed and power but it looks completely different (2nd image). Was I hoping for too much with this??

Sorry for the long post but I feel like banging the head against the wall – I recently seem to be having problems with photos full stop – it’s giving me a crisis of confidence at the moment........

Any suggestions anyone – I have checked all the mirrors/lens etc and all are aligned and clean.

Thanks to all

Karen

PS - just decided maybe I should give it up (for today anyway) and enjoy that rare thing here in Ireland call the sun - it's blistering

[Dan Hintz]

Was the second resize before or after PhotoGrav? It needs to be before...

Also, what resampling method are you using? If you're increasing in size, go with something like a bilinear/cubic and use a sharpening tool after to get back your edges.

[Karen Thompson]

Hi Dan - Thanks for looking - I really hope I didn't sound like a complete eejit (I'm not normally - well most of the time I'm not)

Was the second resize before or after PhotoGrav? It needs to be before...

Resizing for both was done "before" Photograv.

Also, what resampling method are you using? If you're increasing in size, go with something like a bilinear/cubic and use a sharpening tool after to get back your edges.

All I'm doing in Corel Photo-Paint (X4) is Cropping the image first then going to Image-Resample then I put in the size I want and change the DPI (I used 600 on both these images) I haven't been changing any other settings. Then I've just been saving it and going to the next stage.

Karen

[Dave Lock]

Hi Karen,

What setting did you make your scan gap? For a 600 dpi image the scan gap should be set to 0.042

I have found on our Chinese machines that using 300 dpi image can produce a better result, particularly on plywood.
If you give it a go with a 300 dpi image don't forget to change your scan gap to 0.085

I'd be interested in seeing your results.

Regards

Dave.

[Karen Thompson]

Hi Karen,

What setting did you make your scan gap? For a 600 dpi image the scan gap should be set to 0.042

I have found on our Chinese machines that using 300 dpi image can produce a better result, particularly on plywood.
If you give it a go with a 300 dpi image don't forget to change your scan gap to 0.085

I'd be interested in seeing your results.

Regards

Dave.

Hi Dave
Thanks for that - I gave up earlier as it was "doing my 'ead in" and I wanted to make the most of this fantastic weather we're having at the moment . Well overdue!!!!

Anyway - I digress - I think the scan gap was at 0.07 - but I'll try the 300 dpi and see how that goes. I wasn't given any scan gap settings with the machine and didn't see any on the DVD's supplied apart from the materials they demo'd with. So it really has been trial and error......

I'll let you know how it goes. Thanks again Dave.

Karen

[Dave Lock]

Karen,

I have attached a file containing a chart which I think you will fine useful.

It basically shows the dpi (imperial) of your image and what the metric conversion is to use for your scan gap.

It's the amount the y-axis will travel after each pass of the x-axis. It's important that this is set to the same as the resolution of your picture.

You can print it out, cut it to size and stick it on your machine control panel.

Hope it helps.

Dave.

[Karen Thompson]

Dave - Next time I'm in the UK I'll be standing you a pint or two.

Thank you (again)

[Dave Lock]

Dave - Next time I'm in the UK I'll be standing you a pint or two.

Thank you (again)

Just printed that post for future reference

We are all here to help if we can.

Regards

Dave.

[Dave Johnson29]

Dave - Next time I'm in the UK I'll be standing you a pint or two.

Karen,

I have not run Dave's spreadsheet, but I wrote a small free program and posted it here some time back. It reads the actual DPI in both Metric and Imperial (I think) from BMP and JPG files.

If the DPI is not stored with the original JPG, Corel will arbitrarily puts 72 in there. That used to be the old scanning standard for B&W. Not sure why they still do it.

I'll see if I can find that program here and post the link.

Here is the post with a link to my website
http://www.sawmillcreek.org/showpost...85&postcount=1

Ooops, only Imperial, I will make a quick change and replace the copy at that link on my website.

[Karen Thompson]

I think you can "officially" call that a Beer Token

[Karen Thompson]

Dave J - thank you too. Blimey I have alot of homework to do tomorrow

Pints all round I think......

Cheers... !!!

[Dave Johnson29]

Pints all round I think......

Hi Karen, I have updated the program for Metric and it is now on my website under Software.

Bear in mind the program only reads what is in the header and nothing else. The idea of it is to be able to read the DPI etc before loading it into Corel.
If there is no DPI in the header then Corel will incorrectly, in most cases, show 72dpi and save it back out as that.

Make mine a pint of Theakston's Old Peculiar. Yum Theakston's is like peanuts, you can't just have one.

[Karen Thompson]

Make mine a pint of Theakston's Old Peculiar. Yum Theakston's is like peanuts, you can't just have one.

Old Peculiar.......... wow haven't heard of that one in a long time, but no problem I'll remember that just for you

Thank you all once again - about to go and have a play now.
Have a god weekend everyone!!!

Karen

[James Jaragosky]

Hi Karen,

What setting did you make your scan gap? For a 600 dpi image the scan gap should be set to 0.042

I have found on our Chinese machines that using 300 dpi image can produce a better result, particularly on plywood.
If you give it a go with a 300 dpi image don't forget to change your scan gap to 0.085

I'd be interested in seeing your results.

Regards

Dave.

DPI and scan gap question.
I was under the assumption that printing a 300 dpi photo using a 300 dpi ink jet printer; that the printer sprays out tiny dots of ink that are .005 in diameter to form the picture. So if a 300 dpi image is made up of .005 dots******* ///why would you use a scan gap of .085 with a 300 dpi image? Would not a scan gap of .005 work best? That would place the dots exactly next to each other.
I know that my logic is somehow flawed because I currently use a scan gap of .05 and I get acceptable results. ( I will run a test later with a .085 scan gap)
I also was under the assumption that my laser produced a .005 diameter dot at its optimum focal point, this information I obtained from my users specifications.
So am I wrong about the size of the beam dot? What the heck am I missing?

[Dave Lock]

Hi James,

Mentioned earlier in the thread the scan gap is a metric value, it's the metric equivalent to the imperial dpi. You might say its .085mm per inch is the same as 300 dpi.

Regarding the dot size. If the dot measured .005", 300 dots placed exactly next to each other would give you 1.5" so to place them at the side of each other over 1 inch they would overlap by 30%.

If you are currently using .05 as your scan gap that's the same as around 508 dpi. In this case a .005" dot size overlap would be considerable. I have found that so much overlap causes a loss of clarity in the output hence I mainly use images no larger than 300 dpi.


Like most people, when talking about images I think in terms dpi. I find it difficult to work in dots per mm or Cm or whatever it is. Thats why I use the conversion chart. A quick glance at the chart tells me what the scan gap should be for a given dpi.

Sorry if that's about as clear as mud!!

Regards

Dave.