CoolCroco user manual - by Ahmet Yüksek

Installing

Windows

The Microsoft Store build is the easy one: verified by Microsoft, one click, and it keeps itself updated. The standalone installer from the download page works just as well, but Windows SmartScreen may say the publisher is unknown - there is no code-signing certificate behind it yet. Choose More info, then Run anyway. The installer needs no administrator rights and can add a desktop shortcut and Open with → CoolCroco for image files.

macOS

Open the .dmg and drag CoolCroco to Applications. On first launch, right-click the app and choose Open. If macOS says it is damaged, that is only Apple's quarantine flag: open Terminal, type xattr -cr followed by a space, drag the app onto the Terminal window and press Enter. It opens normally after that.

Linux

The AppImage needs no install. Make it executable - chmod +x, or right-click → Properties → Allow executing - then double-click it.

Opening photos

The window sizes itself to the first photo it shows, so a set of portrait frames opens in a portrait window rather than a letterboxed one.

What it opens

RAW from every major brand through LibRaw - Sony, Canon, Nikon, Fujifilm, Olympus, Panasonic, Pentax, Leica, Hasselblad, Phase One, Sigma, Kodak, Minolta, Mamiya, Leaf, Epson and Samsung - plus JPEG, PNG, TIFF, WebP, BMP and the HEIC files an iPhone shoots by default. Straight from the card, no conversion. SVG drawings open too, drawn at a size worth looking at rather than at whatever the file happens to declare.

The window

The title bar carries the file name and your position in the shoot. Top right are two controls: a folder button that opens files, and the menu button - the same menu you get by right-clicking anywhere on the photo.

Along the bottom, the detail bar reads out the photo you are on:

The bar is laid out in columns of a fixed width, so each fact keeps its own place from photograph to photograph and you can watch one number change without chasing it along the bar. Anything too long for its column ends in … and shows in full when you hover it - and hovering the file name shows the photo's full path, which the bar has never had room to print.

Hovering the ? button in the toolbar lists every key, built from your own bindings, so it tells the truth after you rebind something.

Below the photo sits the filmstrip of thumbnails. Drag the divider above it to make it taller or shorter, drag its scrollbar or flick it to travel through a long shoot, and click any thumbnail to jump there.

G gives the whole folder at once: the strip fills the window as a grid, the photograph steps aside, and everything you do to a photograph still works - rate, approve, reject, undo, right-click for the same menu. It is the same filmstrip, so there is no second list of photographs that could disagree with the first. G again brings the photograph back, and so does double-clicking a frame.

A slider appears at the bottom right while the grid is up, and Ctrl and the wheel do the same thing with the pointer over the sheet: bigger cards and fewer of them, or smaller cards and the whole shoot in one screen. Where you leave it is remembered, because how many photographs you want at once is a way of working rather than a setting. The frame you were on is kept in view as the cards resize.

The strip does not have to live at the bottom. Shift+T walks it round the window - left, top, right, bottom, and round again - and Ctrl+Shift+T walks it back. Down a side is the shape to use for an upright shoot: a portrait frame on a wide screen leaves a third of the window empty on either side, and a strip down the side takes room that was doing nothing.

The folder browser

The button at the far left of the toolbar, or Ctrl+B, opens a folder tree down the left-hand side. Click a folder and CoolCroco opens it - one click, the way Bridge and Lightroom do.

What it is most useful for is the folders CoolCroco itself makes. A cull fills Approved, Rejected and Approved\5Stars right beside the shoot, and until now the only way back into them was a file dialog. They are sitting there in the tree.

Drag the divider to resize it; it remembers its width. It opens closed every time, because the photo is what the window is for. The tree follows along, so it always shows where you are however you got there.

The shortcuts above the tree

A tree can only be walked down from a drive letter, and the three folders anybody actually opens are nowhere near the top of one. So above it sits a short list, in the order you reach for them.

Clicking a row opens that folder, exactly as clicking one in the tree does, and the row you are inside stays highlighted - the deepest one, so a shoot in Pictures highlights Pictures rather than Home. A hairline separates each section from the next, and one more separates the whole list from the tree.

The tree tidies itself. Open a folder and the branches you are not in fold away, leaving the way down to where you are and nothing else. What stays open is the folder you just opened - its Approved and Rejected are the reason the tree is here - and everything above it, so the row never folds away from under the click that opened it.

Right-click a folder

Moving through a shoot

Navigation stops at the ends of the folder. The first time you walk off one, CoolCroco asks whether it should loop round to the other end and remembers your answer. A cold folder shows each photo's embedded preview immediately and sharpens to the real decode a moment later, so there is never a black frame to wait through.

Zoom, pan and sticky zoom

Past fit, CoolCroco decodes the photo again at full resolution, so 1:1 really is 1:1 - which is what you want when you are checking focus on a RAW file.

Sticky zoom is for bursts. Zoom into the eye of the first frame, press Z, then arrow through the sequence: every frame of the same size holds the same crop, at full resolution, so you can compare the same detail across ten shots without touching the mouse.

Sorting

Menu → Sort orders the gallery by name, date modified or file size, ascending or descending, and remembers your choice. Star-rated photos always group at the front of the filmstrip - five stars first, down to unrated - whatever sort you pick; the sort orders photos within each of those groups.

Speed and memory

CoolCroco keeps photographs in RAM. That is the whole reason moving through a shoot is instant rather than a wait per frame, and it is why the app asks for a large share of the memory on the machine. Two things in the window are about that.

The green line

A hairline runs along the outer edge of the filmstrip - under it when the strip is along the bottom, outboard of it when the strip is down a side, and along the bottom of the window when the strip is hidden. It fills as the folder is read into memory, so you can see at a glance whether the next frame will appear at once or take a moment.

What counts as full depends on the read-ahead setting. Normally the line measures the neighbourhood - as far either side of the photo on screen as the memory can hold - so a full line means flipping around where you are working is instant, whether or not the rest of a huge card has been read.

The speedometer

At the right-hand end of the status bar, and in Menu → Settings → Preview quality and memory for anyone who never noticed it. It has two dials, and it turns blue whenever either of them is off its default, so a folder behaving unusually explains itself.

Preview quality has five steps, from Lowest to Highest, and sits on High. At the two lowest steps a RAW is read from the preview the camera wrote inside it - a few hundred kilobytes instead of the whole file. Middle and High develop the RAW at half size, which is sharp at any sensible fit on a 4K screen. Highest develops it in full.

It matters most on a slow SD card or card reader, where the time a photograph takes is the time it takes to read off the card. Zoom to 100% and you get the full-resolution file at every one of these settings - nothing on this dial decides how sharp your photographs are, only how quickly they turn up.

The second thing a smaller preview buys is memory. A photograph at half the width costs a quarter of the RAM, so far more of the shoot stays in memory at once and the green line goes further on the same machine.

What it is costing

Beside the speedometer, in dim grey, sits CPU and RAM. The processor figure counts every core on the machine, the way Task Manager does. The memory figure is what is really resident - mostly the photographs being held. Both are a tick box on the speedometer menu if you would rather have the room back.

Read ahead is either Neighbourhood or Whole folder. Neighbourhood is the default: read as far either side of the photo on screen as memory allows, then stop. Whole folder reads everything, which is worth having when the shoot fits, because then nothing ever waits. Dropping the preview quality is what makes a big card fit.

Getting the memory back

A folder you have left is let go of on its own, half a minute after you open the next one. Opening the wrong folder and coming straight back inside that costs nothing; a shoot you have finished with does not sit in memory for the rest of the afternoon.

CoolCroco watches the machine, not just itself. Once about three quarters of your RAM is in use by anything - Lightroom opening beside it, an export running - it starts handing photographs back, taking the frames furthest from the one you are looking at first and never the ones either side of it. It gives up a slice at a time, so a program that needs memory for a moment does not cost you the folder, and it stops as soon as the machine has room again.

Free memory now, on the speedometer menu, does not wait and does not spare the folder you are in. The label says how much it would hand back. The photograph on screen stays exactly where it is, and the frames either side of it are read again as you move - so it costs you the green line and nothing else. Use it when something else on the machine needs the room.

Star ratings

Press 1 to 5 to rate the photo you are looking at; 0 clears the rating. The view moves on to the next photo by itself, and the one you just rated files into its star group at the front of the strip, where its stars show under the thumbnail.

Rate and file, in one keystroke

Hold Shift with a rating - Shift+1 through Shift+5 - and the photo gets that star and moves straight into an Approved\5Stars folder (or 4, 3, 2, 1) beside where it lives now. The rating travels with it, and the view moves on.

Use plain 1–5 when the stars are notes to come back to, and Shift+1–5 when the star is the decision: a shoot sorts itself into star folders as you go, with nothing left to move afterwards.

Ctrl+Z undoes the whole thing at once - the photo comes back to its folder carrying whatever rating it had before you pressed the key. It works on a photo that already has that rating too: pressing Shift+3 on a three-star photo is a request to move it, and it moves.

Filing a whole star group

Right-click any rated thumbnail in the filmstrip and you get two actions for its entire rating tier: move all of them to the matching Approved folder, or copy them there instead - the originals stay exactly where they are, keeping their stars, so you can assemble a print set without emptying the folder it came from. Both are a single undo, and copying the same group twice never overwrites: the second copy lands beside the first.

Picking out a group

Ctrl-click thumbnails in the filmstrip to pick out several, Shift-click to take a run of them, or press Ctrl+A to pick out every one - in the strip or the grid view, and among the frames of the sequences and duplicates window. A plain click still just moves to that photo, so nothing changes until you reach for a modifier.

Right-click the group and everything applies to all of it at once - rotate left or right, rate, approve, reject, or put the lot on the clipboard. Each one counts as a single Ctrl+Z: turning twelve frames costs one undo, not twelve. The group survives the action, so a mixed album can be worked through in one motion.

The keyboard follows the group too. With one picked out, 1 to 5 rates all of it, 0 clears all of it, A and X file all of it, R and Shift+R turn all of it, and Ctrl+Shift+C puts all of it on the clipboard. Delete asks once for the whole group rather than once per photo. With no group picked out, every key does what it always did.

Filing a whole star group

Right-click any rated thumbnail in the filmstrip and you get two actions for its entire rating tier: move all of them to Approved\nStars, so they leave the folder and the gallery, or copy all of them there instead, leaving the originals exactly where they are with their stars intact.

Both are a single undo. Undoing a copy removes the copies and leaves the originals alone. Copying the same group twice never overwrites: the second copy lands beside the first with a number added to its name.

Approve, reject, delete - and undo

Approve and reject are deliberately non-destructive: the subfolder is created next to the photo and the file is moved, not copied or deleted. Its rating sidecar and any EXIF backup travel with it. A and X sit next to each other so one hand can cull while the other holds the coffee.

Undo steps back through everything you did to files in this session: ratings, approve and reject, rate-and-file, group moves and copies, rotations, and EXIF removal. A photo that has left the folder by other means - you moved it yourself, or emptied the subfolder - is skipped rather than failing loudly.

The clipboard

The clipboard is a running selection you paste somewhere else.

Dragging photos out

You can pull a photo straight out of CoolCroco and into whatever is behind it - Photoshop to open it, a browser upload box to post it, an email, a folder in Explorer. No copying to a staging folder first, and no clipboard in between.

With a group picked out, dragging any of it carries all of it, and the group stays picked out afterwards. Drag a thumbnail that is not in the group and only that one photo goes.

Timelapses, bursts and brackets

Analyse → Find sequences looks through the shoot for frames that were taken as one thing - a timelapse on an intervalometer, a burst off the continuous drive, a bracketed set - and offers to file each one into its own subfolder.

A run is recognised by its interval and by the camera staying put: same body, same lens, same focal length, same aperture. A twist of the zoom ends a run, because that is a different shot. Anything faster than about two seconds is called a burst rather than a timelapse, because at that speed the one-second timestamp a camera writes cannot show that an interval was regular.

Tick the runs you agree with, then Move or Copy. Every run goes into its own folder - two runs, two folders, however many frames the button says. Copy is there for a burst you want gathered up without taking it out of the shoot. Either way, however many folders it fills, it is a single Ctrl+Z.

When it has drawn the lines in the wrong place

The detector is working from what the camera wrote down, and you were there. Two things let you overrule it, and neither one touches a file: drag one row onto another to join two runs into one, or highlight a row and click the gap between two frames in the strip below to cut one run in two. Ctrl+Z takes back one step at a time, and Back to what was found returns the whole table.

Naming the folders

The Folder name box builds every name at once from a pattern. The default is kind, date and time - Timelapse 2026-08-14 20-47 - named for when it was shot, so the name still means something a year later. The other tokens are first, last, count and your own word. Type over any single name in the table and the pattern leaves that one alone from then on.

Finding duplicates

Analyse → Find duplicates gathers the frames that are the same photograph and shows them as a group with one picked out to keep - the six you shot as the light kept changing, the file that got copied back onto the card, the frame you re-shot because the first one was soft.

Each row keeps one frame and rejects the rest. Right-click a frame for Keep and Reject to change which, as many as you like, or right-click the row for Keep all and Reject all. Then reject or delete the others from under the table, or move whole groups into folders and decide later. Whichever you press is a single Ctrl+Z.

What it compares is the arrangement of light in the frame, not what the frame is of: each photograph is reduced to sixty-four bits recording which parts of it are brighter than which. Because that is relative brightness it is blind to exposure and white balance, so two frames a stop apart still land together - which is the point, as that is exactly the pair you are trying to choose between. It reads the pictures themselves, so it needs no model download and works whether or not you ever set up searching.

There is no Copy here, and no joining or cutting of groups. Copying a set of duplicates would leave you holding the duplicates and a second set of them. And a group has no boundary to argue with the way the end of a timelapse does: two frames either are the same photograph or they are not, so if one of them does not belong the answer is to keep it, not to cut the group in half.

Filtering the gallery

The funnel button beside the search box, or Ctrl+F, narrows the folder down to part of itself - one lens, one ISO, one afternoon, the five-star frames, the portraits. The two sit together because they are the same question asked two ways: narrow this folder by what the camera recorded, or by what is in the picture.

Every box lists what this folder actually contains, with how many photos carry it. There is nothing to type and nothing to guess at, and a field the folder has only one value for is left out - filtering by the only camera present is a control that cannot do anything. The count at the bottom updates as you go.

Photos that cannot answer are not shown. Ask for ISO 6400 and a file with no EXIF at all stays hidden, because it is not known to be ISO 6400 - but every box offers Unknown as a choice of its own when some files have nothing to say, so you can go and look at them.

Keywords, copyright and the rest

Ctrl+I opens File info - the same set of fields Adobe Bridge shows: title, description, keywords, creator and contact details, location, copyright and usage terms, credit, instructions, job identifier.

Where it gets written

Your star ratings live in the same place - inside a JPEG, in the sidecar for a RAW - so a file never has its keywords in one place and its stars in another.

Editing several at once

With a group picked out in the filmstrip, File info edits all of it. A field the photos disagree on is marked as mixed and is left exactly as it is unless you type in it - so setting the city on twelve photos does not flatten their twelve different titles.

Keywords have three modes. Add, the default, puts yours alongside what each photo already has; Replace swaps them; Remove takes yours out. Templates saves a set of fields - your copyright line and contact details - to apply with two clicks. The whole edit, however many photos, is a single Ctrl+Z.

Searching by what is in the pictures

The box in the toolbar searches the photographs, not the filenames. Type motorcycle and press Enter, and the frames with motorcycles in them come to the front. The vocabulary is open - stars over a lake and red car at sunset work just as well, because nothing here is matching against a list of words.

Nothing is indexed until you search. The first search of a folder reads it once - the magnifying glass turns into a spinner while it does - and writes a small index beside the photos. After that, searching is instant, and only photos that have changed are read again.

Results are ordered, never cut off: every photo keeps a score and the best matches come first, because how well something matches is only meaningful compared with the other answers to the same question. Clear the box to go back to the normal order. A search and a filter work together - filter to one lens, then search inside it.

It is good at objects, animals, vehicles, landscape, weather, the night sky, colour and rough composition; less good at telling one species from a similar one, at specific landmarks and at counting things. It does not read text in a picture, and it does not do people: CoolCroco has no face recognition and is not going to.

Undo and redo

Ctrl+Z steps back through everything you did to files in this session, and Ctrl+Shift+Z puts it back: ratings, approve and reject, rate-and-file, group moves and copies, rotations, and EXIF removal. Each undo reports what it just reversed.

A photo that has left the folder by other means - you moved it in Explorer, or emptied the subfolder yourself - is simply skipped rather than failing loudly.

Rotating for print

R turns the photo a quarter clockwise, Shift+R anticlockwise. The file on disk is turned, not just the view.

Menu → Rotate also has the pass a print run needs. All landscape and All portrait turn only the photos facing the wrong way, so a mixed folder comes out uniform for the paper feed - photos already facing the right way are left untouched. Revert rotations puts the whole folder back the way it arrived, after the run.

Raw exposure

Menu → Settings → Raw exposure. Raw files only: a JPEG arrives already rendered, and so does the small JPEG the camera writes inside every raw - which is what the filmstrip shows you.

The colour behind the photo

Menu → Settings → Background, as a row of swatches. Black is right for judging a bright frame and the worst surround for a dark one - a photo's own blacks disappear into it and every shadow reads as crushed, so you reject frames that were fine.

Weighted towards the dark end on purpose: the rest of this window is nearly black, so a bright surround has black chrome around it and reads as a mistake rather than a choice. Your choice is remembered.

Print size

Menu → Settings → Print size sets the resolution and unit used for the paper measurement in the detail bar. A lab working at 300 dpi in centimetres and someone preparing web images at 72 dpi want different numbers from the same file, so this is set once and remembered. Untick Show in the status bar to hide it again.

Properties and EXIF

Alt+Enter opens everything the file knows about itself: name, folder, type, pixel dimensions and megapixels, print size, bytes, modified and created dates - then the camera block: body, lens, aperture, shutter, ISO, focal length, exposure compensation and the moment it was taken.

Properties and EXIF

Alt+Enter opens everything the file knows about itself: name, folder, type, pixel dimensions and megapixels, print size, bytes, modified and created dates - then the camera block: body, lens, aperture, shutter, ISO, focal length, exposure compensation and the moment it was taken.

Removing EXIF data

Menu → EXIF data → Remove EXIF data. Tick what should go - GPS location, camera, lens and serial numbers, capture settings, date and time, software, artist and copyright - and it is stripped from the open photo. Groups the file does not carry are greyed out, so you can see at a glance whether a photo is even carrying its location.

• Pixels are never recompressed. Only the JPEG's EXIF segment is rewritten; the compressed image data is copied through byte for byte.
• With the backup box ticked, the original EXIF is saved beside the photo. It travels with the file when you approve or reject, and goes to the Recycle Bin with it if you delete.
• Recover EXIF data puts it back from that backup. Unlike undo, it still works on a photo you stripped days ago.
• Don't show this dialog again makes later removals happen in one keystroke with the same choices. Bring the prompt back with Ask before removing EXIF in the same menu.

Opening in another app

Menu → Open in. The first time, pick your editor; it is remembered by name after that, and Change external editor swaps it. Give it a key in the shortcuts dialog and a photo goes to Lightroom or Photoshop with one press. Open with hands the photo to the system's own chooser for a one-off app, and L opens the photo's location - Explorer with the file selected, Finder on macOS, the containing folder on Linux. If another program rewrites a photo you have open, CoolCroco notices when you come back to the window and reloads it.

Opening in another app

If another program rewrites a photo you have open, CoolCroco notices when you come back to the window and reloads it, so what you see is never a stale copy of a file you just edited elsewhere.

Making the keys yours

Menu → Settings → Keyboard shortcuts. Double-click an action, or select it and press F2, then press the combination you want. Esc cancels, Clear leaves an action with no key, and Restore Defaults puts everything back. Changes take effect immediately - there is no restart.

• Actions with several keys - Next is the right arrow, PgDn, Down and Space - keep their alternates; only the first key changes.
• The rating keys 1–5 and Shift+1–5 are fixed and cannot be reassigned or taken by something else.
• A key already in use is refused the moment you press it, naming the action that has it.
• Remove EXIF data, Recover EXIF data, Open with and Open in editor ship with no key at all - assign them here if you use them often.

All keys

What CoolCroco writes, and where

Nothing is written inside your photos except when you explicitly rotate one or remove its EXIF. Everything else lives beside them:

Preferences - sort order, print size, your shortcut changes, the remembered editor - are stored per user, outside your photo folders.

Updates

The version from this website checks for a new release on startup and offers it; turn that off under Settings → Check for updates on startup. The Microsoft Store version updates through the Store. Menu → What's new shows what changed in each release.