Issue with preparing scans for print using LR

[aleksander_kelpman]

 

 

I've used photoshop for preparing digital prints before with no problem, <br />but there are some features in lightroom I quite enjoy, so I'd love <br />to overcome an obstacle. Maybe you can help?<br /><br />I import tiff files scanned with silverfast, then do my adjustments and

when I export them and then look at image size using photoshop

I notice the document size has shrunk over 2/3rds, for example from 40cm width to 12cm width.

 

Resample is unticked, dpi is 300 throughout.

 

 

 

 

 

[JosvanEekelen]

I think at this stage you can forget the size ( in cm/inch) rating. The size in pixels should have remained the same. If not

check all settings because then you seem to have altered the size.

[aleksander_kelpman]

<p>The size in pixels did remain the same.</p>

[Ed_Ingold]

<p>Size does matter, at least when printing. Photoshop and Lightroom may adjust the output to a printer so that the designated size is produced, based on the printer's characteristics. You can also elect to fill the available space, but the ability to print to a specific size has it's benefits.</p>

<p>When you export an image from Lightroom, there is a section in which you can specify the output size and resolution, with or without resampling. The resolution may default to 240 ppi, which changes the print dimensions proportionately but keeps the number of pixels the same. You can also resample to an exact size and resolution.</p>

<p>Choices!</p>

[aleksander_kelpman]

<p>You can't increase the document size (printing dimensions) without sacrificing the dpi.<br />In my current situation I need to print the photos 40cm width at 300dpi.</p>

[Ed_Ingold]

 

 

<blockquote>

<p>You can't increase the document size (printing dimensions) without sacrificing the dpi.<br />In my current situation I need to print the photos 40cm width at 300dpi.</p>

</blockquote>

 

 

You can resample as needed to set any size and/or DPI for an image.

 

 

 

There is nothing sacrosanct about 300 dpi for printing. You can't see pixelation in a print as low as 240 dpi, possibly lower depending on the subject, or for very large prints. The print driver will resample as needed to multiples of the basic printer resolution. However resampling in Photoshop or another program may give smoother results.

 

 

 

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[aleksander_kelpman]

<p>Increasing the document size in photoshop from 12cm to 40cm will lower the dpi to 104.<br />Although I've read about the dpi being not set in stone in terms of image quality, I wouldn't<br />like to take my chances. It's a magazine cover and I won't have a chance to make test prints.<br />It's clear for some reason lightroom alters the print dimensions in my scans.</p>

[aleksander_kelpman]

<p>A note of interest might be that I scanned the photos at 1600dpi, when I opened them up in photoshop and changed the resolution from 1600 to 300, the document size was initially correct.</p>

[aleksander_kelpman]

<p>To clarify, it was initially correct at 300dpi. At 1600dpi it was obviously much lower.</p>

[digitaldog]

<p>Work with pixels. That's a fixed attribute of the data unless of course you resample that data (add or remove pixels).</p>

<p>You are referring to what is a resolution tag and it's rather meaningless. It could be 72PPI or 180PPI or 300PPI,but it doesn't have an inherent meaning, only what you could produce with the number of pixels you have at your disposal. Work with pixels! For example, let us say you have 1000x1000 pixels to keep the math simple. And to simplify this further, let's only consider the horizontal axis. If you have 1000 pixels and divide that by 72, that is, you provide 72 pixels per inch, you could end up with 13.8 inches using that division (1000/72=13.8). Let's now say you divide up your 1000 pixels using 180 instead. 1000/180=5.5. In both cases, you had 1000 total pixels. The document itself doesn't have a size, other than what space it takes up on your hard drive. The sizes above are examples of what could be produced if you divided up the total number of pixels you have, with some number of which is just a tag within the document. In Photoshop, if you use the Image Size dialog, turn resample OFF (do not allow it to create more or remove pixels), you can enter any value, 72, 180, 1000 into the resolution field and the resulting size is calculated for you. But you haven’t changed the document or the data at all. You just changed a theoretical 'size' if you output your 1000 pixels using that resolution. So again, it's meaningless until you output the data. At that point, lets say you print the image, you can decide how big you wish it to appear and/or how many pixels you want to devote to the output. You have 1000 pixels and someone tells you that you must use 300DPI (which isn't true but that's a different story). 1000/300 would produce a 3.3 inch print. You want a bigger print? Lower the DPI (within reason). You set the DPI for output to use 180 of your pixels to produce 180DPI? You get a 5.5 inch print (1000/180=5.5).</p>

 

[aleksander_kelpman]

<p>Thank you for the thorough explanation, Andrew.<br /><br />I still wonder WHY the lightroom export module alters the document size in such way that the pixels, doc size and dpi are not in correlation with each other. Why go through a tirade with a photo editor every time you want to send 100dpi files. People tend to be not the most cooperative while working on a tight schedule and their jobs on the line. <br />I've found a reroute using lightroom's print module, but it's a tedious workaround since you need to calculate your file dimensions every time so you wouldn't lose pixel data.</p>

[aleksander_kelpman]

The same thing happens with digital raw file exports as well.

 

http://i.cubeupload.com/m5c4nj.jpg

 

In this example, making a quick calculation, while the pixel size is 1600 x 1067 and ppi is 300, the document size should be 13,55 x 9,03cm.

http://www.photokaboom.com/photography/learn/printing/1_calculators.htm

Is my software somehow strangely broken? I haven't come across this problem online.

[cosmic_c]

You need to check the units your using - what you show above is in cm, so please keep in mind that 300 ppi (pixels per inch) is very different to 300 pixels per cm

[aleksander_kelpman]

Oh yes! I wonder if it changed if I switched my units to metric or when did I manage to switch it.

 

Anyhow, thanks a lot, very helpful!

[cosmic_c]

Oh yes! I wonder if it changed if I switched my units to metric or when did I manage to switch it.

Anyhow, thanks a lot, very helpful!

 

Your welcome, I suspect your right, it may have changed when you switched units to metric.