What sort of printer is requiring 600ppi?
If your printer is 600 dpi you can save those images as 150 ppi and be fine. You’re confusing printer resolution (DPI) with image resolution (PPI).
Bob
Perhaps I didn’t explain properly.
I have an image which is an arbitrary number of pixels wide. In the image is an object of know size, say a coin. I wish to print this image at 600dpi (no, I’m not confused) such that the coin comes out life-size, and the rest of the image is at this same scale.
Any clearer?
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http://www.scantips.com>
Bookmark it first, then scroll down and start reading at *Start
This isn’t the lazy answer, it’s the smart answer that will pay off the best for you in the long run.
🙂
Nope. It sounds as if you haven’t grasped the relationship between pixel dimensions, linear dimensions and resolution.
Phos4: The images have already been created, and are photographs. John: I have grasped these concepts, but perhaps need to explain in words of one syllable.
Do you guys need to see an example? See below:
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http://www.mercier.org.uk/temp/penny.jpg>
This is an image of a penny, and a lid. You see it has been cropped to the sides of the penny, which has a width of 20.3mm. This was done by selecting Crop: Width 20.3mm @ Resolution 600 pixels/inch. If I print this on my 600dpi Laser printer, it comes out actual size. With me so far?
However, I don’t want to crop the image, as I have now lost the subject of the image (the lid). I just want to automatically resize it so it prints at the same scale.
Nigel…
It’s a brilliant bit of info anyway. Learn it or be forever dependent upon others to suss the resolution/image size math for you.
The 600ppi in the image has nothing to do with the resolution that your printer is capable of printing. As was mentioned previously, you could use a lower resolution just fine, as long as the image itself was still the actual size you’re looking for. If you want a penny that’s 20.3mm, just make sure you’ve sized it to 20.3mm in your image. There are measurement tools that can help you out there, guidelines that can be placed, etc.
The 600ppi in the image has nothing to do with the resolution that your printer is capable of printing.
Perhaps not, but it keeps the resolution at maximum
If you want a penny that’s 20.3mm, just make sure you’ve sized it to 20.3mm in your image. There are measurement tools that can help you out there, guidelines that can be placed, etc.
But no automatic method, like the crop tool?
Ah, I see what you’re trying to get at. Btw, if you’re using the crop tool to change the size and resolution, you may simply be interpolating the pixels, which means making up pixels that aren’t there. You can’t get any better quality out of the image than what was originally captured, so if you’re upping the resolution to 600ppi thinking that, it’s a pointless exercise. You usually only need about 300ppi at the print size to get good quality. The 600ppi in a printer spec has no correlation to the resolution of a bitmap image.
Read through the site that was linked earlier, as it will help you understand the ins and outs of size and resolution. I’ll give you a tip on how to accomplish what you want, but if you don’t understand what you are doing, or if it’s even necessary, you may be doing needless work at best, or at worst, degrading your image while thinking you are making it acceptable for print instead of getting a better capture from the outset.
Turn your image into a layer and specify the size you need, NOT the resolution. If you’re only concerned about getting the size right, you crop your image to that size. After the crop it will adjust the resolution without interpolating pixels and you can see what kind of resolution you have to work with.
Before executing the crop, look up in the options bar and set the cropped area to "hide," then crop it. The resolution will adjust to give you all the pixels encapsulated in the penny without altering them. Then you can go to Image-Reveal all to show all of your image again. Keep in mind that the size of the original image may be changed to reflect the change in resolution.
if you’re using the crop tool to change the size and resolution, you may simply be interpolating the pixels, which means making up pixels that aren’t there.
That’s not a problem.
The whole purpose of the exercise is to get a printout of an object (the lid in my example) at its actual size (the size of the object, not the size of the image) when that size is *not* known, but the size of something else in the image (the penny) *is* known.
Perhaps I should give the reasons why I want to do this. I often take photographs to show the shape and size of an object. Somewhere in this photograph I include an object of known size, or a ruler. When I get home I can then reproduce the object at its actual size.
Yes, it usually helps to know what you’re trying to achieve instead of just asking the question of how to do something with some preconceived notions of what you think will get you there. I’ve seen it often where someone who needs photoshop help is asking how to do something, then we find out what it is they are trying to achieve and tell them about a much easier method to get them there than what they were pigeon-holing themselves with.
Anyway, the method I described gets you what you want, without interpolating the image.
Nigel,
I understand what you’re asking for: a way to resample the image so an object in the image prints at life size for a given print resolution (in your case a preference of 600 PPI).
I think it should be possible to write a script (an action would not be powerful enough to do the calcs) to do this, at least partially, but a quick Google did not turn up anything that I could see except a similar but slightly different request on these forums (not a good sign).
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http://www.adobeforums.com/webx/.3bbf2765.59b5869d>
It is possible that Photoshop Extended might be able to do what you want, since it has more sophisticated measurement and scaling tools but I don’t have Extended and the feature descriptions for Extended are a little ambiguous for me.
The only other non-scripting solution I can think of would be to use the ruler tool to measure the object and then use a calculator or something to calculate the percentage of upsampling or downsampling needed. Of course I realize that would involve some of the work you are trying to avoid.
I think therefore your options are:
– keep doing what you’re doing
– calculate the upsample/downsample
– write a script or pay/beg for the development of one
similar but slightly different request on these forums …
Indeed, that is what I wanted.
Oh well, thanks all for trying to help.
On the positive side, I do have Extended, so I’ll look further.
Nigel: Here is a method that may work for you.
(1) Since you have PSCS4, you are able to convert your image to a smart object.
(2) Create a layer mask that corresponds to the physical size you would want the known object to print at. E.g., your known object (the coin) is 20.3mm wide, so you create a rectangular marquee that is 20.3mm wide:
(a) Create an arbitrary sized rectangular marquee, then use Select->Transform Selection and enter the desired height and width into the object bar (e.g., 20.3mm 20.3mm) and
commit. It doesn’t matter where in the image you make this; all that matters is that you have a 20.3×20.3mm marquee.
(b) Turn this marquee into a mask by clicking on the masks panel and then the icon second from the right. Unlock the mask from the smart object by clicking on the chain icon.
(3) Use this layer mask to calibrate the image against the known object:
(a) Click on the smart object icon in the layer, then use Edit->Transform (with the aspect ratio locked) to move the known object (coin) into the mask and scale it so it just barely fits into its width.
(b) Your smart object is now scaled properly in Photoshop. You should now delete (or disable) the layer mask, which is no longer needed.
(4) Use the Move tool, if necessary, and the Rectangular Marquee tool to select the area of the image to be printed.
(5) In the Print dialog, set scale to 100%. Don’t use borderless printing, which typically reduces the printing scale slightly.
(b) Turn this marquee into a mask by clicking on the masks panel and then the icon second from the right.
Can you clarify this for me please – what does the icon say?
Read my post #11. I’ve given you the method that will easily give you exactly what you want in 2 simple steps. 3 if you have to turn a background image into a layer.
Photoshop and your printer driver will resample your image to whatever resolution you have set in your printer drive so there is no need to resample your when you are adjusting the inches or cms to be real size.
I am going to repeat a more step-by-step version of Peter’s procedure which seems less complicated than the smart-object method / layer-mask / transform method.
1) Convert your background image to a Layer if not already.
2) Select the Crop tool icon.
3) Before defining the crop area, in the crop-options up top, type in the dimensions of the object you are going to measure (the lid) specifying both the number and the units (like 4 in or 10 cm or something). If your object is round then you can specify one dimension accurately and make the other one very small, like 4 in x 1 mm.
4) Blank out the resolution field in the options if there is any number and/or units in it.
5) Click-drag your crop-marquee to encompass or span the object you entered the dimensions of (the lid). If you specified one dimension very small compared to the accurate one (like 80mm x 1mm) then you will have a long thin ruler you can drag across the object from one side to the other which may be easier than trying to guess a corner of a round object. Adjust the crop tool corners as needed to exactly match the object that you know the size of.
6) Make sure the crop tool option is set to Hide not Delete. This option won’t be available if your image is not a layer so it needs to be a layer.
7) Click the Apply checkbox up top or just hit Enter.
8) Select Image / Reveal All from the menu.
There you are, your image has the right scale for printing.
If you want to verify turn on the grid with View / Show > Grid and perhaps also turn on the Rulers using View / Rulers.
Hi Steve,
Perfect! I have added one last step:
9) Clear crop dimensions, then re-crop just the part of the image you want to print.
Thank you so much.
Nigel
I wasn’t going to guess what you’d want to do as the next step. Maybe you had 10 images with the same lid to crop before you would move on to the printing so need the same dimensions remaining for several iterations.
If you find yourself using the same reference object(s) over and over and so need the same crop dimensions, then create yourself a preset:
After you type in the dimensions (like 4 in x 1 mm) then click the down-arrow by the crop-tool in the options bar (not the tool bar further below) and choose the little new-page icon on the right of the dropdown of presets and you can save the current numbers as a new preset for use from the drop down any time. You can even save a blanked-out crop tool option set as a preset.
However, instead of blanking out the dimensions, just use the Selection tool marquee (the dotted-line toolbar icon) followed by Image / Crop to remove excess image before printing.
Nigel,
It sounds like you already have a good approach or two in hand, but here is an alternative approach since you have two great assets: a known size object in the image and the extended edition of Photoshop.
1) Zoom in on the object of known dimension so it fills a good portion of your window.
2) Click on Analysis then on the Ruler Tool from its drop down menu.
3) Click and drag the ruler tool from edge to edge of the object of known dimension. This dimension in pixels will be presented in the ruler results box.
4) Divide that pixel count by the known dimension to give you the calibrated metric of pixels per inch in your photo.
5) Click on Image then Image Size and uncheck the resample box; then type the computed pixels/inch into the resolution box.
6) Crop the image if you want and then print at a scale of 100% and you get an actual size rendition. Your result will be independent of your printer’s resolution and no resampling of your photograph occurs.
Paulo
