Is there such a thing as a simple answer in the Adobe world??? 😭😭😭

To michybas71:  After carefully reviewing this string and evaluating your struggle, I highly support the expert advice given by the four Community Pros.  

It may be helpful to just create a colour palette of your favourites, for now, until your designer returns.  If the designer provided only print samples, they may have had a very practical reason to do so.  One reason may be that the project did ask for print materials, to start; the second reason is that the designer will suspect that your monitor(s) of devices are not calibrated.

Experience shows that what people see on their monitors, generally, is far from accurate or correct, and is almost never what they saw it as, before being printed - unless it is directed by someone who uses calibrated devices and knows colour - someone like the designer.  

So even if you "see" and think that #1f305e is "the colour" it will not be "that colour" when printed on different materials, and as compared to being viewed on an un-calibrated device.   The designer probably wants to give you a WYSIWYG example - hence the print.  

However, if you are determined to solve this for yourself, this last suggestion is a hack and full of potential for bad outcomes:  With a reasonably decent digital camera take a snap of each of the printed materials, in daylight (not direct sunlight) and with a grey-card or grey point reference in each frame.  This will give you an actual digital camera-image that you can open directly in Photoshop.

From the rest of the advice and direction given by the Pros in this string, you can then apply subject selection and colour changes to your heart's desire, ... or until your designer returns.

Wish you all the best outcomes!

F. Quill

PS v22..., LR, OM-D EM ... 

I have to admit that you almost lost me in your very first paragraph in which you suggested that creativity and science are mutually exclusive. For starters, how would you shoehorn Einstein’s extraordinary thought experiments into that statement?  In addition, as a person headed for surgery, be thankful that those two elements -- science and creativity -- are totally compatible, should an unexpected and unprepared for event present itself. 

I will leave the Photoshop part of your request to the expert advice offered by my pal @jane-e and add one more suggestion:

In your post you wrote “…print some rough samples off to pass around friends and family for feedback.” If you are serious about your product or service it would be prudent to reach  out to a marketing expert experienced in sales to your chosen audience, and rely in large measure on his or her advice regarding your logo and auxiliary printed material. Your family and friends, wonderful and well-intentioned as they may be, are no match for a professional in the creative and scientific fields of market research and prediction. Simply, it's worth the bucks.  

Quick tricks and instructions written for the stem brain if that fails:

Super simple, very bad:

press the foreground color in the toolbar on the right. That's the two overlapping boxes, the bigger pair, the upper one. You get a color mixer. Pick your color.

Long-press the last button in the toolbar on the left side, usually it's three dots. You should see a menu, and on it you should find the Paint Bucket tool. Use the paint bucket tool to fill your selected color into the color areas. 

Done.

Still simple, slightly better.
if it's a computer generated file with completly flat colors (no shadows or gradients), you can just use the magic wand tool to select the color area. If the color is in many areas, hold down the shift button on your keyboard to pick multiple areas. 

Then you should have the part selected. To make the selection more loose, or less loose, change the Tolerance, it's a number box up top, under the menu. It only appears while the magic wand is selected. 

Once you have what you want selected, mix the color you want by pressing the foreground color, then use alt-backspace (on the mac) to fill the region. If you're on the pc, it's either alt or one of those buttons in that region. Experiment!

Done.

If you're happy with the selection, but want a method that helps you change things quickly over and over, just do this: While you have a selection that you like, go into the layers pallete. Press the circle which is half black and half white, choose Solid Color, pick a color, press enter. Then you have an object, a layer object in fact, you can change over and over. Just double-click it.  

If this is really not working, it's time to figure out why not. And since you're a molecular biologist, I'm gonna venture and say that theory might help where long-winding tutorials failed.

Art Nerd Stuff For Stem Nerd Peeps:

I'm gonna tell you a bit about colors and transparency, maybe that will make what the tools do self-evident. I don't know what you know, so skip over what you find obvious.

Simple color picking really only works when the colors are flat. If your designer did the logo with flat colors in illustrator, and it hasn't been printed and then photographed or scanned, this should work. But if the logo has shadows or colors that wash into each other, you are no longer making a simple mathematical selection. It's not one point in the color spectrum, but a grouping, a cluster in a field.

You understand color values. You may well know most of this. To explain these tools, I'm gonna present them as dimensions. Grayscale is one dimension. Just a line that starts at black and ends at white. RGB is three dimensions, for each of those colors. RGB is measured light. So in one corner you have black, all the lights are off. one corner is white, all lights on. and everywhere else is different mixtures of the three colors, as lights mix. CMYK is paints mixing. Let's just 0skip that.

There is another color mode, and its easier to understand. HSB, hue saturation brightness. 

I like HSB because it's the easiest to understand, and it's the most powerful way to change colors. Brightness: Brighter, darker. Saturation: Stronger color or more muted. So zero saturation is gray. A picture rich in colors is saturated. Hue? that's the color wheel. The rainbow. So if you move the hue slider, you're sliding across the rainbow scale. Or color wheel scale if rainbow talk is to unicorny.

Get your head around HSB and photoshop is your oyster. 

Anyway. 

If you pick just one color, it's one dot in that space. The color selection tools expand the dot into a sphere. 

Photoshop has one more dimension: transparency. A mask adds a transparency channel to the red green and blue channels, so you can see through some bits and some not, and some are quasi-transparent. A selection is just a temporary transparency channel.

The magic wand creates a crude, hard line selection, just thinks in hard black and hard white. Select > Color Range uses a fuzzy ball in the color space to capture the range of colors you want, more or less. 

If neither work, Select > Select and Mask uses AI to automagic things, and you have to instruct it with brushes that work in a very abstract way. It's the absolute best of the lot, quickest too, but the only way to learn how to use it is just to mess around with it. 

Hope you're ok with the language, I go simple and slow so you can speed-read and jump up and down to create the mental picture, that's what works for me. 

Since you have a rasterized version of the logo, you can't go in and select the paths and change their fill directly. One way is to select colors with "Color Range" in the Select menu. Eyedropper the color you want to select, edit fuzziness if there are gradients or to tweak the selection. White areas are being selected, black is not. Once you have your marching ant selection, you can edit it more with Select and Mask in the Select menu, or use the Lasso tool to trim or add parts. Ok, with your selection, make a Solid Color adjustment layer, which will make a new layer of color with an automatically created mask of your selection that you had selected. Do this over and over for all your key colors. If you have 4 colors, you will have 4 layers now on top of your original. You are just stacking layers upon layers in Photoshop! Hope this works!

Create a custom palette (color table) and use that to convert to Indexed color.

https://helpx.adobe.com/photoshop/using/converting-color-modes.html

https://helpx.adobe.com/photoshop/using/customizing-indexed-color-tables.html

The reason you're having such as hard time is because Photoshop is a pixel-based photo editing app. Logos are usually vector graphics created in Illustrator. In Illustrator making such a change would be much easier (assuming you have the original vector file, and not a version that was converted to pixels). A pixel-based file (such as a scan, or file exported from Illustrator as a PNG, JPEG, etc) will not be as easy to edit because the elements are not seperate shapes as they originally were in Illustrator.

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@MIchBas wrote:

As I obviously don't have the digital files yet, for the purposes of what I'd like to visualise I've simply scanned the logo samples into PDFs which I've opened up in Photoshop. My intention was to simply change the colours of each of the logo components to each of the potential options, and print some rough samples off to pass around friends and family for feedback.

Hi

The first question is: what application did your designer use to create the logo samples? Typically, logos are done in Illustrator. If you have the Illustrator file, there are several easy ways to change the colors, including the Recolor Artwork command.

If she/he did it in PS instead, they used layers, and it would still be doable, but not as easily.

But what you've done is scan the printed file, so everything is on one layer and Photoshop is looking at pixels, not logo components. To change the colors, you'll need to select each set of pixels that make up what you think of as a component, then put it on a new layer and change the color. Your success will depend on how good your selection skills are. You can use the selection tools, commands in the Selection menu, or draw paths with the Pen tool.

How good are your Photoshop skills?

~ Jane